## String Utility Functions

String Utility Functions — various string-related functions

## Synopsis

    #include <glib.h>
    #include <glib/gprintf.h>

    gchar*              g_strdup                            (const gchar *str);
    gchar*              g_strndup                           (const gchar *str,
                                                             gsize n);
    gchar**             g_strdupv                           (gchar **str_array);
    gchar*              g_strnfill                          (gsize length,
                                                             gchar fill_char);
    gchar*              g_stpcpy                            (gchar *dest,
                                                             const char *src);
    gchar *             g_strstr_len                        (const gchar *haystack,
                                                             gssize haystack_len,
                                                             const gchar *needle);
    gchar *             g_strrstr                           (const gchar *haystack,
                                                             const gchar *needle);
    gchar *             g_strrstr_len                       (const gchar *haystack,
                                                             gssize haystack_len,
                                                             const gchar *needle);
    gboolean            g_str_has_prefix                    (const gchar *str,
                                                             const gchar *prefix);
    gboolean            g_str_has_suffix                    (const gchar *str,
                                                             const gchar *suffix);
    int                 g_strcmp0                           (const char *str1,
                                                             const char *str2);

    gsize               g_strlcpy                           (gchar *dest,
                                                             const gchar *src,
                                                             gsize dest_size);
    gsize               g_strlcat                           (gchar *dest,
                                                             const gchar *src,
                                                             gsize dest_size);

    gchar*              g_strdup_printf                     (const gchar *format,
                                                             ...);
    gchar*              g_strdup_vprintf                    (const gchar *format,
                                                             va_list args);
    gint                g_printf                            (gchar const *format,
                                                             ...);
    gint                g_vprintf                           (gchar const *format,
                                                             va_list args);
    gint                g_fprintf                           (FILE *file,
                                                             gchar const *format,
                                                             ...);
    gint                g_vfprintf                          (FILE *file,
                                                             gchar const *format,
                                                             va_list args);
    gint                g_sprintf                           (gchar *string,
                                                             gchar const *format,
                                                             ...);
    gint                g_vsprintf                          (gchar *string,
                                                             gchar const *format,
                                                             va_list args);
    gint                g_snprintf                          (gchar *string,
                                                             gulong n,
                                                             gchar const *format,
                                                             ...);
    gint                g_vsnprintf                         (gchar *string,
                                                             gulong n,
                                                             gchar const *format,
                                                             va_list args);
    gint                g_vasprintf                         (gchar **string,
                                                             gchar const *format,
                                                             va_list args);
    gsize               g_printf_string_upper_bound         (const gchar *format,
                                                             va_list args);

    gboolean            g_ascii_isalnum                     (gchar c);
    gboolean            g_ascii_isalpha                     (gchar c);
    gboolean            g_ascii_iscntrl                     (gchar c);
    gboolean            g_ascii_isdigit                     (gchar c);
    gboolean            g_ascii_isgraph                     (gchar c);
    gboolean            g_ascii_islower                     (gchar c);
    gboolean            g_ascii_isprint                     (gchar c);
    gboolean            g_ascii_ispunct                     (gchar c);
    gboolean            g_ascii_isspace                     (gchar c);
    gboolean            g_ascii_isupper                     (gchar c);
    gboolean            g_ascii_isxdigit                    (gchar c);

    gint                g_ascii_digit_value                 (gchar c);
    gint                g_ascii_xdigit_value                (gchar c);

    gint                g_ascii_strcasecmp                  (const gchar *s1,
                                                             const gchar *s2);
    gint                g_ascii_strncasecmp                 (const gchar *s1,
                                                             const gchar *s2,
                                                             gsize n);

    gchar*              g_ascii_strup                       (const gchar *str,
                                                             gssize len);
    gchar*              g_ascii_strdown                     (const gchar *str,
                                                             gssize len);

    gchar               g_ascii_tolower                     (gchar c);
    gchar               g_ascii_toupper                     (gchar c);

    GString*            g_string_ascii_up                   (GString *string);
    GString*            g_string_ascii_down                 (GString *string);

    gchar*              g_strup                             (gchar *string);
    gchar*              g_strdown                           (gchar *string);

    gint                g_strcasecmp                        (const gchar *s1,
                                                             const gchar *s2);
    gint                g_strncasecmp                       (const gchar *s1,
                                                             const gchar *s2,
                                                             guint n);

    gchar*              g_strreverse                        (gchar *string);

    gint64              g_ascii_strtoll                     (const gchar *nptr,
                                                             gchar **endptr,
                                                             guint base);
    guint64             g_ascii_strtoull                    (const gchar *nptr,
                                                             gchar **endptr,
                                                             guint base);
    #define             G_ASCII_DTOSTR_BUF_SIZE
    gdouble             g_ascii_strtod                      (const gchar *nptr,
                                                             gchar **endptr);
    gchar *             g_ascii_dtostr                      (gchar *buffer,
                                                             gint buf_len,
                                                             gdouble d);
    gchar *             g_ascii_formatd                     (gchar *buffer,
                                                             gint buf_len,
                                                             const gchar *format,
                                                             gdouble d);
    gdouble             g_strtod                            (const gchar *nptr,
                                                             gchar **endptr);

    gchar*              g_strchug                           (gchar *string);
    gchar*              g_strchomp                          (gchar *string);
    #define             g_strstrip                          ( string )

    gchar*              g_strdelimit                        (gchar *string,
                                                             const gchar *delimiters,
                                                             gchar new_delimiter);
    #define             G_STR_DELIMITERS
    gchar*              g_strescape                         (const gchar *source,
                                                             const gchar *exceptions);
    gchar*              g_strcompress                       (const gchar *source);
    gchar*              g_strcanon                          (gchar *string,
                                                             const gchar *valid_chars,
                                                             gchar substitutor);
    gchar**             g_strsplit                          (const gchar *string,
                                                             const gchar *delimiter,
                                                             gint max_tokens);
    gchar **            g_strsplit_set                      (const gchar *string,
                                                             const gchar *delimiters,
                                                             gint max_tokens);
    void                g_strfreev                          (gchar **str_array);
    gchar*              g_strconcat                         (const gchar *string1,
                                                             ...);
    gchar*              g_strjoin                           (const gchar *separator,
                                                             ...);
    gchar*              g_strjoinv                          (const gchar *separator,
                                                             gchar **str_array);
    guint               g_strv_length                       (gchar **str_array);

    const gchar*        g_strerror                          (gint errnum);
    const gchar*        g_strsignal                         (gint signum);

## Description

This section describes a number of utility functions for creating, duplicating, and manipulating strings.

Note that the functions `g_printf()`, `g_fprintf()`, `g_sprintf()`, `g_snprintf()`, `g_vprintf()`, `g_vfprintf()`, `g_vsprintf()` and `g_vsnprintf()` are declared in the header `gprintf.h` which is not included in `glib.h` (otherwise using `glib.h` would drag in `stdio.h`), so you'll have to explicitly include `<glib/gprintf.h>` in order to use the GLib `printf()` functions.

While you may use the `printf()` functions to format UTF-8 strings, notice that the precision of a `%Ns` parameter is interpreted as the number of bytes, not characters to print. On top of that, the GNU libc implementation of the `printf()` functions has the "feature" that it checks that the string given for the `%Ns` parameter consists of a whole number of characters in the current encoding. So, unless you are sure you are always going to be in an UTF-8 locale or your know your text is restricted to ASCII, avoid using `%Ns`. If your intention is to format strings for a certain number of columns, then `%Ns` is not a correct solution anyway, since it fails to take wide characters (see `g_unichar_iswide()`) into account.

## Details

### g_strdup ()

    gchar*              g_strdup                            (const gchar *str);

Duplicates a string. If `str` is `NULL` it returns `NULL`. The returned string should be freed when no longer needed.

`str` : | the string to duplicate.
Returns : | a newly-allocated copy of `str`.

### g_strndup ()

    gchar*              g_strndup                           (const gchar *str,
                                                             gsize n);

Duplicates the first `n` bytes of a string, returning a newly-allocated buffer `n` + 1 bytes long which will always be nul-terminated. If `str` is less than `n` bytes long the buffer is padded with nuls. If `str` is `NULL` it returns `NULL`. The returned value should be freed when no longer needed.

### Note

To copy a number of characters from a UTF-8 encoded string, use `g_utf8_strncpy()` instead.

`str` : | the string to duplicate
`n` : | the maximum number of bytes to copy from `str`
Returns : | a newly-allocated buffer containing the first `n` bytes of `str`, nul-terminated

### g_strdupv ()

    gchar**             g_strdupv                           (gchar **str_array);

Copies `NULL`-terminated array of strings. The copy is a deep copy; the new array should be freed by first freeing each string, then the array itself. `g_strfreev()` does this for you. If called on a `NULL` value, `g_strdupv()` simply returns `NULL`.

`str_array` : | `NULL`-terminated array of strings.
Returns : | a new `NULL`-terminated array of strings.

### g_strnfill ()

    gchar*              g_strnfill                          (gsize length,
                                                             gchar fill_char);

Creates a new string `length` bytes long filled with `fill_char`. The returned string should be freed when no longer needed.

`length` : | the length of the new string
`fill_char` : | the byte to fill the string with
Returns : | a newly-allocated string filled the `fill_char`

### g_stpcpy ()

    gchar*              g_stpcpy                            (gchar *dest,
                                                             const char *src);

Copies a nul-terminated string into the dest buffer, include the trailing nul, and return a pointer to the trailing nul byte. This is useful for concatenating multiple strings together without having to repeatedly scan for the end.

`dest` : | destination buffer.
`src` : | source string.
Returns : | a pointer to trailing nul byte.

### g_strstr_len ()

    gchar *             g_strstr_len                        (const gchar *haystack,
                                                             gssize haystack_len,
                                                             const gchar *needle);

Searches the string `haystack` for the first occurrence of the string `needle`, limiting the length of the search to `haystack_len`.

`haystack` : | a string.
`haystack_len` : | the maximum length of `haystack`. Note that -1 is a valid length, if `haystack` is nul-terminated, meaning it will search through the whole string.
`needle` : | the string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_strrstr ()

    gchar *             g_strrstr                           (const gchar *haystack,
                                                             const gchar *needle);

Searches the string `haystack` for the last occurrence of the string `needle`.

`haystack` : | a nul-terminated string.
`needle` : | the nul-terminated string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_strrstr_len ()

    gchar *             g_strrstr_len                       (const gchar *haystack,
                                                             gssize haystack_len,
                                                             const gchar *needle);

Searches the string `haystack` for the last occurrence of the string `needle`, limiting the length of the search to `haystack_len`.

`haystack` : | a nul-terminated string.
`haystack_len` : | the maximum length of `haystack`.
`needle` : | the nul-terminated string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_str_has_prefix ()

    gboolean            g_str_has_prefix                    (const gchar *str,
                                                             const gchar *prefix);

Looks whether the string `str` begins with `prefix`.

`str` : | a nul-terminated string.
`prefix` : | the nul-terminated prefix to look for.
Returns : | `TRUE` if `str` begins with `prefix`, `FALSE` otherwise.

Since 2.2

### g_str_has_suffix ()

    gboolean            g_str_has_suffix                    (const gchar *str,
                                                             const gchar *suffix);

Looks whether the string `str` ends with `suffix`.

`str` : | a nul-terminated string.
`suffix` : | the nul-terminated suffix to look for.
Returns : | `TRUE` if `str` end with `suffix`, `FALSE` otherwise.

Since 2.2

### g_strcmp0 ()

    int                 g_strcmp0                           (const char *str1,
                                                             const char *str2);

Compares `str1` and `str2` like `strcmp()`. Handles `NULL` strings gracefully.

`str1` : | a C string or `NULL`
`str2` : | another C string or `NULL`
Returns : | -1, 0 or 1, if `str1` is <, == or > than `str2`.

Since 2.16

### g_strlcpy ()

    gsize               g_strlcpy                           (gchar *dest,
                                                             const gchar *src,
                                                             gsize dest_size);

Portability wrapper that calls `strlcpy()` on systems which have it, and emulates `strlcpy()` otherwise. Copies `src` to `dest`; `dest` is guaranteed to be nul-terminated; `src` must be nul-terminated; `dest_size` is the buffer size, not the number of chars to copy. Caveat: `strlcpy()` is supposedly more secure than `strcpy()` or `strncpy()`, but if you really want to avoid screwups, `g_strdup()` is an even better idea.

`dest` : | destination buffer
`src` : | source buffer
`dest_size` : | length of `dest` in bytes
Returns : | length of `src`

### g_strlcat ()

    gsize               g_strlcat                           (gchar *dest,
                                                             const gchar *src,
                                                             gsize dest_size);

Portability wrapper that calls `strlcat()` on systems which have it, and emulates it otherwise. Appends nul-terminated `src` string to `dest`, guaranteeing nul-termination for `dest`. The total size of `dest` won't exceed `dest_size`. Caveat: this is supposedly a more secure alternative to `strcat()` or `strncat()`, but for real security `g_strconcat()` is harder to mess up.

`dest` : | destination buffer, already containing one nul-terminated string
`src` : | source buffer
`dest_size` : | length of `dest` buffer in bytes (not length of existing string inside `dest`)
Returns : | length of `src` plus initial length of string in `dest`

### g_strdup_printf ()

    gchar*              g_strdup_printf                     (const gchar *format,
                                                             ...);

Similar to the standard C `sprintf()` function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed when no longer needed.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the parameters to insert into the format string.
Returns : | a newly-allocated string holding the result.

### g_strdup_vprintf ()

    gchar*              g_strdup_vprintf                    (const gchar *format,
                                                             va_list args);

Similar to the standard C `vsprintf()` function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed when no longer needed.

See also `g_vasprintf()`, which offers the same functionality, but additionally returns the length of the allocated string.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of parameters to insert into the format string.
Returns : | a newly-allocated string holding the result.

### g_printf ()

    gint                g_printf                            (gchar const *format,
                                                             ...);

An implementation of the standard `printf()` function which supports positional parameters, as specified in the Single Unix Specification.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_vprintf ()

    gint                g_vprintf                           (gchar const *format,
                                                             va_list args);

An implementation of the standard `vprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_fprintf ()

    gint                g_fprintf                           (FILE *file,
                                                             gchar const *format,
                                                             ...);

An implementation of the standard `fprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`file` : | the stream to write to.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_vfprintf ()

    gint                g_vfprintf                          (FILE *file,
                                                             gchar const *format,
                                                             va_list args);

An implementation of the standard `fprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`file` : | the stream to write to.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_sprintf ()

    gint                g_sprintf                           (gchar *string,
                                                             gchar const *format,
                                                             ...);

An implementation of the standard `sprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`string` : | A pointer to a memory buffer to contain the resulting string. It is up to the caller to ensure that the allocated buffer is large enough to hold the formatted result
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_vsprintf ()

    gint                g_vsprintf                          (gchar *string,
                                                             gchar const *format,
                                                             va_list args);

An implementation of the standard `vsprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.2

### g_snprintf ()

    gint                g_snprintf                          (gchar *string,
                                                             gulong n,
                                                             gchar const *format,
                                                             ...);

A safer form of the standard `sprintf()` function. The output is guaranteed to not exceed `n` characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also `g_strdup_printf()`.

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of `g_snprintf()` conforms to the `snprintf()` function as standardized in ISO C99. Note that this is different from traditional `snprintf()`, which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`n` : | the maximum number of bytes to produce (including the terminating nul character).
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of bytes which would be produced if the buffer was large enough.

### g_vsnprintf ()

    gint                g_vsnprintf                         (gchar *string,
                                                             gulong n,
                                                             gchar const *format,
                                                             va_list args);

A safer form of the standard `vsprintf()` function. The output is guaranteed to not exceed `n` characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also `g_strdup_vprintf()`.

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of `g_vsnprintf()` conforms to the `vsnprintf()` function as standardized in ISO C99. Note that this is different from traditional `vsnprintf()`, which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`n` : | the maximum number of bytes to produce (including the terminating nul character).
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of bytes which would be produced if the buffer was large enough.

### g_vasprintf ()

    gint                g_vasprintf                         (gchar **string,
                                                             gchar const *format,
                                                             va_list args);

An implementation of the GNU `vasprintf()` function which supports positional parameters, as specified in the Single Unix Specification. This function is similar to `g_vsprintf()`, except that it allocates a string to hold the output, instead of putting the output in a buffer you allocate in advance.

`string` : | the return location for the newly-allocated string.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of bytes printed.

Since 2.4

### g_printf_string_upper_bound ()

    gsize               g_printf_string_upper_bound         (const gchar *format,
                                                             va_list args);

Calculates the maximum space needed to store the output of the `sprintf()` function.

`format` : | the format string. See the `printf()` documentation.
`args` : | the parameters to be inserted into the format string.
Returns : | the maximum space needed to store the formatted string.

### g_ascii_isalnum ()

    gboolean            g_ascii_isalnum                     (gchar c);

Determines whether a character is alphanumeric.

Unlike the standard C library `isalnum()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII alphanumeric character

### g_ascii_isalpha ()

    gboolean            g_ascii_isalpha                     (gchar c);

Determines whether a character is alphabetic (i.e. a letter).

Unlike the standard C library `isalpha()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII alphabetic character

### g_ascii_iscntrl ()

    gboolean            g_ascii_iscntrl                     (gchar c);

Determines whether a character is a control character.

Unlike the standard C library `iscntrl()` function, this only recognizes standard ASCII control characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII control character.

### g_ascii_isdigit ()

    gboolean            g_ascii_isdigit                     (gchar c);

Determines whether a character is digit (0-9).

Unlike the standard C library `isdigit()` function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII digit.

### g_ascii_isgraph ()

    gboolean            g_ascii_isgraph                     (gchar c);

Determines whether a character is a printing character and not a space.

Unlike the standard C library `isgraph()` function, this only recognizes standard ASCII characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII printing character other than space.

### g_ascii_islower ()

    gboolean            g_ascii_islower                     (gchar c);

Determines whether a character is an ASCII lower case letter.

Unlike the standard C library `islower()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII lower case letter

### g_ascii_isprint ()

    gboolean            g_ascii_isprint                     (gchar c);

Determines whether a character is a printing character.

Unlike the standard C library `isprint()` function, this only recognizes standard ASCII characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII printing character.

### g_ascii_ispunct ()

    gboolean            g_ascii_ispunct                     (gchar c);

Determines whether a character is a punctuation character.

Unlike the standard C library `ispunct()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII punctuation character.

### g_ascii_isspace ()

    gboolean            g_ascii_isspace                     (gchar c);

Determines whether a character is a white-space character.

Unlike the standard C library `isspace()` function, this only recognizes standard ASCII white-space and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII white-space character

### g_ascii_isupper ()

    gboolean            g_ascii_isupper                     (gchar c);

Determines whether a character is an ASCII upper case letter.

Unlike the standard C library `isupper()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII upper case letter

### g_ascii_isxdigit ()

    gboolean            g_ascii_isxdigit                    (gchar c);

Determines whether a character is a hexadecimal-digit character.

Unlike the standard C library `isxdigit()` function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | %TRUE if `c` is an ASCII hexadecimal-digit character.

### g_ascii_digit_value ()

    gint                g_ascii_digit_value                 (gchar c);

Determines the numeric value of a character as a decimal digit. Differs from `g_unichar_digit_value()` because it takes a char, so there's no worry about sign extension if characters are signed.

`c` : | an ASCII character.
Returns : | If `c` is a decimal digit (according to `g_ascii_isdigit()`), its numeric value. Otherwise, -1.

### g_ascii_xdigit_value ()

    gint                g_ascii_xdigit_value                (gchar c);

Determines the numeric value of a character as a hexidecimal digit. Differs from `g_unichar_xdigit_value()` because it takes a char, so there's no worry about sign extension if characters are signed.

`c` : | an ASCII character.
Returns : | If `c` is a hex digit (according to `g_ascii_isxdigit()`), its numeric value. Otherwise, -1.

### g_ascii_strcasecmp ()

    gint                g_ascii_strcasecmp                  (const gchar *s1,
                                                             const gchar *s2);

Compare two strings, ignoring the case of ASCII characters.

Unlike the BSD `strcasecmp()` function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII bytes as if they are not letters.

This function should be used only on strings that are known to be in encodings where the bytes corresponding to ASCII letters always represent themselves. This includes UTF-8 and the ISO-8859-* charsets, but not for instance double-byte encodings like the Windows Codepage 932, where the trailing bytes of double-byte characters include all ASCII letters. If you compare two CP932 strings using this function, you will get false matches.

`s1` : | string to compare with `s2`.
`s2` : | string to compare with `s1`.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_ascii_strncasecmp ()

    gint                g_ascii_strncasecmp                 (const gchar *s1,
                                                             const gchar *s2,
                                                             gsize n);

Compare `s1` and `s2`, ignoring the case of ASCII characters and any characters after the first `n` in each string.

Unlike the BSD `strcasecmp()` function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII characters as if they are not letters.

The same warning as in `g_ascii_strcasecmp()` applies: Use this function only on strings known to be in encodings where bytes corresponding to ASCII letters always represent themselves.

`s1` : | string to compare with `s2`.
`s2` : | string to compare with `s1`.
`n` : | number of characters to compare.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_ascii_strup ()

    gchar*              g_ascii_strup                       (const gchar *str,
                                                             gssize len);

Converts all lower case ASCII letters to upper case ASCII letters.

`str` : | a string.
`len` : | length of `str` in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string, with all the lower case characters in `str` converted to upper case, with semantics that exactly match `g_ascii_toupper()`. (Note that this is unlike the old `g_strup()`, which modified the string in place.)

### g_ascii_strdown ()

    gchar*              g_ascii_strdown                     (const gchar *str,
                                                             gssize len);

Converts all upper case ASCII letters to lower case ASCII letters.

`str` : | a string.
`len` : | length of `str` in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly-allocated string, with all the upper case characters in `str` converted to lower case, with semantics that exactly match `g_ascii_tolower()`. (Note that this is unlike the old `g_strdown()`, which modified the string in place.)

### g_ascii_tolower ()

    gchar               g_ascii_tolower                     (gchar c);

Convert a character to ASCII lower case.

Unlike the standard C library `tolower()` function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are lower case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character.
Returns : | the result of converting `c` to lower case. If `c` is not an ASCII upper case letter, `c` is returned unchanged.

### g_ascii_toupper ()

    gchar               g_ascii_toupper                     (gchar c);

Convert a character to ASCII upper case.

Unlike the standard C library `toupper()` function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are upper case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character.
Returns : | the result of converting `c` to upper case. If `c` is not an ASCII lower case letter, `c` is returned unchanged.

### g_string_ascii_up ()

    GString*            g_string_ascii_up                   (GString *string);

Converts all lower case ASCII letters to upper case ASCII letters.

`string` : | a GString
Returns : | passed-in `string` pointer, with all the lower case characters converted to upper case in place, with semantics that exactly match `g_ascii_toupper()`.

### g_string_ascii_down ()

    GString*            g_string_ascii_down                 (GString *string);

Converts all upper case ASCII letters to lower case ASCII letters.

`string` : | a GString
Returns : | passed-in `string` pointer, with all the upper case characters converted to lower case in place, with semantics that exactly match `g_ascii_tolower()`.

### g_strup ()

    gchar*              g_strup                             (gchar *string);

### Warning

`g_strup` has been deprecated since version 2.2 and should not be used in newly-written code. This function is totally broken for the reasons discussed in the `g_strncasecmp()` docs - use `g_ascii_strup()` or `g_utf8_strup()` instead.

Converts a string to upper case.

`string` : | the string to convert.
Returns : | the string

### g_strdown ()

    gchar*              g_strdown                           (gchar *string);

### Warning

`g_strdown` has been deprecated since version 2.2 and should not be used in newly-written code. This function is totally broken for the reasons discussed in the `g_strncasecmp()` docs - use `g_ascii_strdown()` or `g_utf8_strdown()` instead.

Converts a string to lower case.

`string` : | the string to convert.
Returns : | the string

### g_strcasecmp ()

    gint                g_strcasecmp                        (const gchar *s1,
                                                             const gchar *s2);

### Warning

`g_strcasecmp` has been deprecated since version 2.2 and should not be used in newly-written code. See `g_strncasecmp()` for a discussion of why this function is deprecated and how to replace it.

A case-insensitive string comparison, corresponding to the standard `strcasecmp()` function on platforms which support it.

`s1` : | a string.
`s2` : | a string to compare with `s1`.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_strncasecmp ()

    gint                g_strncasecmp                       (const gchar *s1,
                                                             const gchar *s2,
                                                             guint n);

### Warning

`g_strncasecmp` has been deprecated since version 2.2 and should not be used in newly-written code. The problem with `g_strncasecmp()` is that it does the comparison by calling `toupper()`/`tolower()`. These functions are locale-specific and operate on single bytes. However, it is impossible to handle things correctly from an I18N standpoint by operating on bytes, since characters may be multibyte. Thus `g_strncasecmp()` is broken if your string is guaranteed to be ASCII, since it's locale-sensitive, and it's broken if your string is localized, since it doesn't work on many encodings at all, including UTF-8, EUC-JP, etc.

There are therefore two replacement functions: `g_ascii_strncasecmp()`, which only works on ASCII and is not locale-sensitive, and `g_utf8_casefold()`, which is good for case-insensitive sorting of UTF-8.

A case-insensitive string comparison, corresponding to the standard `strncasecmp()` function on platforms which support it. It is similar to `g_strcasecmp()` except it only compares the first `n` characters of the strings.

`s1` : | a string.
`s2` : | a string to compare with `s1`.
`n` : | the maximum number of characters to compare.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_strreverse ()

    gchar*              g_strreverse                        (gchar *string);

Reverses all of the bytes in a string. For example, `g_strreverse ("abcdef")` will result in "fedcba".

Note that `g_strreverse()` doesn't work on UTF-8 strings containing multibyte characters. For that purpose, use `g_utf8_strreverse()`.

`string` : | the string to reverse.
Returns : | the same pointer passed in as `string`.

### g_ascii_strtoll ()

    gint64              g_ascii_strtoll                     (const gchar *nptr,
                                                             gchar **endptr,
                                                             guint base);

Converts a string to a gint64 value. This function behaves like the standard `strtoll()` function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system `strtoll()` function.

If the correct value would cause overflow, `G_MAXINT64` or `G_MININT64` is returned, and `ERANGE` is stored in `errno`. If the base is outside the valid range, zero is returned, and `EINVAL` is stored in `errno`. If the string conversion fails, zero is returned, and `endptr` returns `nptr` (if `endptr` is non-`NULL`).

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
`base` : | to be used for the conversion, 2..36 or 0
Returns : | the gint64 value or zero on error.

Since 2.12

### g_ascii_strtoull ()

    guint64             g_ascii_strtoull                    (const gchar *nptr,
                                                             gchar **endptr,
                                                             guint base);

Converts a string to a guint64 value. This function behaves like the standard `strtoull()` function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system `strtoull()` function.

If the correct value would cause overflow, `G_MAXUINT64` is returned, and `ERANGE` is stored in `errno`. If the base is outside the valid range, zero is returned, and `EINVAL` is stored in `errno`. If the string conversion fails, zero is returned, and `endptr` returns `nptr` (if `endptr` is non-`NULL`).

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
`base` : | to be used for the conversion, 2..36 or 0
Returns : | the guint64 value or zero on error.

Since 2.2

### G_ASCII_DTOSTR_BUF_SIZE

    #define G_ASCII_DTOSTR_BUF_SIZE (29 + 10)

A good size for a buffer to be passed into `g_ascii_dtostr()`. It is guaranteed to be enough for all output of that function on systems with 64bit IEEE-compatible doubles.

The typical usage would be something like:

      char buf[G_ASCII_DTOSTR_BUF_SIZE];
      fprintf (out, "value=%s\n", g_ascii_dtostr (buf, sizeof (buf), value));

### g_ascii_strtod ()

    gdouble             g_ascii_strtod                      (const gchar *nptr,
                                                             gchar **endptr);

Converts a string to a gdouble value.

This function behaves like the standard `strtod()` function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe. A limitation of the implementation is that this function will still accept localized versions of infinities and NANs.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system `strtod()` function.

To convert from a gdouble to a string in a locale-insensitive way, use `g_ascii_dtostr()`.

If the correct value would cause overflow, plus or minus `HUGE_VAL` is returned (according to the sign of the value), and `ERANGE` is stored in `errno`. If the correct value would cause underflow, zero is returned and `ERANGE` is stored in `errno`.

This function resets `errno` before calling `strtod()` so that you can reliably detect overflow and underflow.

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
Returns : | the gdouble value.

### g_ascii_dtostr ()

    gchar *             g_ascii_dtostr                      (gchar *buffer,
                                                             gint buf_len,
                                                             gdouble d);

Converts a gdouble to a string, using the '.' as decimal point.

This functions generates enough precision that converting the string back using `g_ascii_strtod()` gives the same machine-number (on machines with IEEE compatible 64bit doubles). It is guaranteed that the size of the resulting string will never be larger than `G_ASCII_DTOSTR_BUF_SIZE` bytes.

`buffer` : | A buffer to place the resulting string in
`buf_len` : | The length of the buffer.
`d` : | The gdouble to convert
Returns : | The pointer to the buffer with the converted string.

### g_ascii_formatd ()

    gchar *             g_ascii_formatd                     (gchar *buffer,
                                                             gint buf_len,
                                                             const gchar *format,
                                                             gdouble d);

Converts a gdouble to a string, using the '.' as decimal point. To format the number you pass in a `printf()`-style format string. Allowed conversion specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.

If you just want to want to serialize the value into a string, use `g_ascii_dtostr()`.

`buffer` : | A buffer to place the resulting string in
`buf_len` : | The length of the buffer.
`format` : | The `printf()`-style format to use for the code to use for converting.
`d` : | The gdouble to convert
Returns : | The pointer to the buffer with the converted string.

### g_strtod ()

    gdouble             g_strtod                            (const gchar *nptr,
                                                             gchar **endptr);

Converts a string to a gdouble value. It calls the standard `strtod()` function to handle the conversion, but if the string is not completely converted it attempts the conversion again with `g_ascii_strtod()`, and returns the best match.

This function should seldomly be used. The normal situation when reading numbers not for human consumption is to use `g_ascii_strtod()`. Only when you know that you must expect both locale formatted and C formatted numbers should you use this. Make sure that you don't pass strings such as comma separated lists of values, since the commas may be interpreted as a decimal point in some locales, causing unexpected results.

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
Returns : | the gdouble value.

### g_strchug ()

    gchar*              g_strchug                           (gchar *string);

Removes leading whitespace from a string, by moving the rest of the characters forward.

This function doesn't allocate or reallocate any memory; it modifies `string` in place. The pointer to `string` is returned to allow the nesting of functions.

Also see `g_strchomp()` and `g_strstrip()`.

`string` : | a string to remove the leading whitespace from.
Returns : | @string.

### g_strchomp ()

    gchar*              g_strchomp                          (gchar *string);

Removes trailing whitespace from a string.

This function doesn't allocate or reallocate any memory; it modifies `string` in place. The pointer to `string` is returned to allow the nesting of functions.

Also see `g_strchug()` and `g_strstrip()`.

`string` : | a string to remove the trailing whitespace from.
Returns : | @string.

### g_strstrip()

    #define             g_strstrip( string )

Removes leading and trailing whitespace from a string. See `g_strchomp()` and `g_strchug()`.

`string` : | a string to remove the leading and trailing whitespace from.

### g_strdelimit ()

    gchar*              g_strdelimit                        (gchar *string,
                                                             const gchar *delimiters,
                                                             gchar new_delimiter);

Converts any delimiter characters in `string` to `new_delimiter`. Any characters in `string` which are found in `delimiters` are changed to the `new_delimiter` character. Modifies `string` in place, and returns `string` itself, not a copy. The return value is to allow nesting such as `g_ascii_strup (g_strdelimit (str, "abc", '?'))`.

`string` : | the string to convert.
`delimiters` : | a string containing the current delimiters, or `NULL` to use the standard delimiters defined in G_STR_DELIMITERS.
`new_delimiter` : | the new delimiter character.
Returns : | @string.

### G_STR_DELIMITERS

    #define	 G_STR_DELIMITERS	"_-|> <."

The standard delimiters, used in `g_strdelimit()`.

### g_strescape ()

    gchar*              g_strescape                         (const gchar *source,
                                                             const gchar *exceptions);

Escapes the special characters '\b', '\f', '\n', '\r', '\t', '\' and '"' in the string `source` by inserting a '\' before them. Additionally all characters in the range 0x01-0x1F (everything below SPACE) and in the range 0x7F-0xFF (all non-ASCII chars) are replaced with a '\' followed by their octal representation. Characters supplied in `exceptions` are not escaped.

`g_strcompress()` does the reverse conversion.

`source` : | a string to escape.
`exceptions` : | a string of characters not to escape in `source`.
Returns : | a newly-allocated copy of `source` with certain characters escaped. See above.

### g_strcompress ()

    gchar*              g_strcompress                       (const gchar *source);

Replaces all escaped characters with their one byte equivalent. It does the reverse conversion of `g_strescape()`.

`source` : | a string to compress.
Returns : | a newly-allocated copy of `source` with all escaped character compressed.

### g_strcanon ()

    gchar*              g_strcanon                          (gchar *string,
                                                             const gchar *valid_chars,
                                                             gchar substitutor);

For each character in `string`, if the character is not in `valid_chars`, replaces the character with `substitutor`. Modifies `string` in place, and return `string` itself, not a copy. The return value is to allow nesting such as `g_ascii_strup (g_strcanon (str, "abc", '?'))`.

`string` : | a nul-terminated array of bytes.
`valid_chars` : | bytes permitted in `string`.
`substitutor` : | replacement character for disallowed bytes.
Returns : | @string.

### g_strsplit ()

    gchar**             g_strsplit                          (const gchar *string,
                                                             const gchar *delimiter,
                                                             gint max_tokens);

Splits a string into a maximum of `max_tokens` pieces, using the given `delimiter`. If `max_tokens` is reached, the remainder of `string` is appended to the last token.

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling `g_strsplit()`.

`string` : | a string to split.
`delimiter` : | a string which specifies the places at which to split the string. The delimiter is not included in any of the resulting strings, unless `max_tokens` is reached.
`max_tokens` : | the maximum number of pieces to split `string` into. If this is less than 1, the string is split completely.
Returns : | a newly-allocated `NULL`-terminated array of strings. Use `g_strfreev()` to free it.

### g_strsplit_set ()

    gchar **            g_strsplit_set                      (const gchar *string,
                                                             const gchar *delimiters,
                                                             gint max_tokens);

Splits `string` into a number of tokens not containing any of the characters in `delimiter`. A token is the (possibly empty) longest string that does not contain any of the characters in `delimiters`. If `max_tokens` is reached, the remainder is appended to the last token.

For example the result of g_strsplit_set ("abc:def/ghi", ":/", -1) is a `NULL`-terminated vector containing the three strings "abc", "def", and "ghi".

The result if g_strsplit_set (":def/ghi:", ":/", -1) is a `NULL`-terminated vector containing the four strings "", "def", "ghi", and "".

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling `g_strsplit_set()`.

Note that this function works on bytes not characters, so it can't be used to delimit UTF-8 strings for anything but ASCII characters.

`string` : | The string to be tokenized
`delimiters` : | A nul-terminated string containing bytes that are used to split the string.
`max_tokens` : | The maximum number of tokens to split `string` into. If this is less than 1, the string is split completely
Returns : | a newly-allocated `NULL`-terminated array of strings. Use `g_strfreev()` to free it.

Since 2.4

### g_strfreev ()

    void                g_strfreev                          (gchar **str_array);

Frees a `NULL`-terminated array of strings, and the array itself. If called on a `NULL` value, `g_strfreev()` simply returns.

`str_array` : | a `NULL`-terminated array of strings to free.

### g_strconcat ()

    gchar*              g_strconcat                         (const gchar *string1,
                                                             ...);

Concatenates all of the given strings into one long string. The returned string should be freed when no longer needed.

### Warning

The variable argument list must end with `NULL`. If you forget the `NULL`, `g_strconcat()` will start appending random memory junk to your string.

`string1` : | The first string to add, which must not be `NULL`.
`...` : | a `NULL`-terminated list of strings to append to the string.
Returns : | a newly-allocated string containing all the string arguments.

### g_strjoin ()

    gchar*              g_strjoin                           (const gchar *separator,
                                                             ...);

Joins a number of strings together to form one long string, with the optional `separator` inserted between each of them.

`separator` : | a string to insert between each of the strings, or `NULL`.
`...` : | a `NULL`-terminated list of strings to join.
Returns : | a newly-allocated string containing all of the strings joined together, with `separator` between them.

### g_strjoinv ()

    gchar*              g_strjoinv                          (const gchar *separator,
                                                             gchar **str_array);

Joins a number of strings together to form one long string, with the optional `separator` inserted between each of them.

`separator` : | a string to insert between each of the strings, or `NULL`.
`str_array` : | a `NULL`-terminated array of strings to join.
Returns : | a newly-allocated string containing all of the strings joined together, with `separator` between them.

### g_strv_length ()

    guint               g_strv_length                       (gchar **str_array);

Returns the length of the given `NULL`-terminated string array `str_array`.

`str_array` : | a `NULL`-terminated array of strings.
Returns : | length of `str_array`.

Since 2.6

### g_strerror ()

    const gchar*        g_strerror                          (gint errnum);

Returns a string corresponding to the given error code, e.g. "no such process". You should use this function in preference to `strerror()`, because it returns a string in UTF-8 encoding, and since not all platforms support the `strerror()` function.

`errnum` : | the system error number. See the standard C `errno` documentation.
Returns : | a UTF-8 string describing the error code. If the error code is unknown, it returns "unknown error (<code>)". The string can only be used until the next call to `g_strerror()`.

### g_strsignal ()

    const gchar*        g_strsignal                         (gint signum);

Returns a string describing the given signal, e.g. "Segmentation fault". You should use this function in preference to `strsignal()`, because it returns a string in UTF-8 encoding, and since not all platforms support the `strsignal()` function.

`signum` : | the signal number. See the `signal` documentation.
Returns : | a UTF-8 string describing the signal. If the signal is unknown, it returns "unknown signal (<signum>)". The string can only be used until the next call to `g_strsignal()`.