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# Character Set Conversion

## Name

Character Set Conversion -- convert strings between different character sets using `iconv()`.

## Synopsis

    #include <glib.h>

    gchar*      g_convert                       (const gchar *str,
                                                 gssize len,
                                                 const gchar *to_codeset,
                                                 const gchar *from_codeset,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    gchar*      g_convert_with_fallback         (const gchar *str,
                                                 gssize len,
                                                 const gchar *to_codeset,
                                                 const gchar *from_codeset,
                                                 gchar *fallback,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    gchar*      g_convert_with_iconv            (const gchar *str,
                                                 gssize len,
                                                 GIConv converter,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    #define     G_CONVERT_ERROR
    GIConv      g_iconv_open                    (const gchar *to_codeset,
                                                 const gchar *from_codeset);
    size_t      g_iconv                         (GIConv converter,
                                                 gchar **inbuf,
                                                 gsize *inbytes_left,
                                                 gchar **outbuf,
                                                 gsize *outbytes_left);
    gint        g_iconv_close                   (GIConv converter);
    gchar*      g_locale_to_utf8                (const gchar *opsysstring,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    gchar*      g_filename_to_utf8              (const gchar *opsysstring,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    gchar*      g_filename_from_utf8            (const gchar *utf8string,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    gchar*      g_filename_from_uri             (const char *uri,
                                                 char **hostname,
                                                 GError **error);
    gchar*      g_filename_to_uri               (const char *filename,
                                                 const char *hostname,
                                                 GError **error);
    gchar*      g_locale_from_utf8              (const gchar *utf8string,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);
    enum        GConvertError;

    gboolean    g_get_charset                   (G_CONST_RETURN char **charset);

## Description

## Details

### g_convert ()

    gchar*      g_convert                       (const gchar *str,
                                                 gssize len,
                                                 const gchar *to_codeset,
                                                 const gchar *from_codeset,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string from one character set to another.

`str` : | the string to convert
`len` : | the length of the string
`to_codeset` : | name of character set into which to convert `str`
`from_codeset` : | character set of `str`.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | If the conversion was successful, a newly allocated nul-terminated string, which must be freed with g_free(). Otherwise `NULL` and `error` will be set.

### g_convert_with_fallback ()

    gchar*      g_convert_with_fallback         (const gchar *str,
                                                 gssize len,
                                                 const gchar *to_codeset,
                                                 const gchar *from_codeset,
                                                 gchar *fallback,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string from one character set to another, possibly including fallback sequences for characters not representable in the output. Note that it is not guaranteed that the specification for the fallback sequences in `fallback` will be honored. Some systems may do a approximate conversion from `from_codeset` to `to_codeset` in their `iconv()` functions, in which case GLib will simply return that approximate conversion.

`str` : | the string to convert
`len` : | the length of the string
`to_codeset` : | name of character set into which to convert `str`
`from_codeset` : | character set of `str`.
`fallback` : | UTF-8 string to use in place of character not present in the target encoding. (This must be in the target encoding), if `NULL`, characters not in the target encoding will be represented as Unicode escapes \x{XXXX} or \x{XXXXXX}.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | If the conversion was successful, a newly allocated nul-terminated string, which must be freed with g_free(). Otherwise `NULL` and `error` will be set.

### g_convert_with_iconv ()

    gchar*      g_convert_with_iconv            (const gchar *str,
                                                 gssize len,
                                                 GIConv converter,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string from one character set to another.

`str` : | the string to convert
`len` : | the length of the string
`converter` : | conversion descriptor from g_iconv_open()
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | If the conversion was successful, a newly allocated nul-terminated string, which must be freed with g_free(). Otherwise `NULL` and `error` will be set.

### G_CONVERT_ERROR

    #define G_CONVERT_ERROR g_convert_error_quark()

Error domain for character set conversions. Errors in this domain will be from the GConvertError enumeration. See GError for information on error domains.

### g_iconv_open ()

    GIConv      g_iconv_open                    (const gchar *to_codeset,
                                                 const gchar *from_codeset);

Same as the standard UNIX routine `iconv_open()`, but may be implemented via libiconv on UNIX flavors that lack a native implementation.

GLib provides g_convert() and g_locale_to_utf8() which are likely more convenient than the raw iconv wrappers.

`to_codeset` : | destination codeset
`from_codeset` : | source codeset
Returns : | a "conversion descriptor"

### g_iconv ()

    size_t      g_iconv                         (GIConv converter,
                                                 gchar **inbuf,
                                                 gsize *inbytes_left,
                                                 gchar **outbuf,
                                                 gsize *outbytes_left);

Same as the standard UNIX routine `iconv()`, but may be implemented via libiconv on UNIX flavors that lack a native implementation.

GLib provides g_convert() and g_locale_to_utf8() which are likely more convenient than the raw iconv wrappers.

`converter` : | conversion descriptor from g_iconv_open()
`inbuf` : | bytes to convert
`inbytes_left` : | inout parameter, bytes remaining to convert in `inbuf`
`outbuf` : | converted output bytes
`outbytes_left` : | inout parameter, bytes available to fill in `outbuf`
Returns : | count of non-reversible conversions, or -1 on error

### g_iconv_close ()

    gint        g_iconv_close                   (GIConv converter);

Same as the standard UNIX routine `iconv_close()`, but may be implemented via libiconv on UNIX flavors that lack a native implementation. Should be called to clean up the conversion descriptor from g_iconv_open() when you are done converting things.

GLib provides g_convert() and g_locale_to_utf8() which are likely more convenient than the raw iconv wrappers.

`converter` : | a conversion descriptor from g_iconv_open()
Returns : | -1 on error, 0 on success

### g_locale_to_utf8 ()

    gchar*      g_locale_to_utf8                (const gchar *opsysstring,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string which is in the encoding used for strings by the C runtime (usually the same as that used by the operating system) in the current locale into a UTF-8 string.

`opsysstring` : | a string in the encoding of the current locale
`len` : | the length of the string, or -1 if the string is nul-terminated.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | The converted string, or `NULL` on an error.

### g_filename_to_utf8 ()

    gchar*      g_filename_to_utf8              (const gchar *opsysstring,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string which is in the encoding used for filenames into a UTF-8 string.

`opsysstring` : | a string in the encoding for filenames
`len` : | the length of the string, or -1 if the string is nul-terminated.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | The converted string, or `NULL` on an error.

### g_filename_from_utf8 ()

    gchar*      g_filename_from_utf8            (const gchar *utf8string,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string from UTF-8 to the encoding used for filenames.

`utf8string` : | a UTF-8 encoded string.
`len` : | the length of the string, or -1 if the string is nul-terminated.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | The converted string, or `NULL` on an error.

### g_filename_from_uri ()

    gchar*      g_filename_from_uri             (const char *uri,
                                                 char **hostname,
                                                 GError **error);

Converts an escaped UTF-8 encoded URI to a local filename in the encoding used for filenames.

`uri` : | a uri describing a filename (escaped, encoded in UTF-8).
`hostname` : | Location to store hostname for the URI, or `NULL`. If there is no hostname in the URI, `NULL` will be stored in this location.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | a newly-allocated string holding the resulting filename, or `NULL` on an error.

### g_filename_to_uri ()

    gchar*      g_filename_to_uri               (const char *filename,
                                                 const char *hostname,
                                                 GError **error);

Converts an absolute filename to an escaped UTF-8 encoded URI.

`filename` : | an absolute filename specified in the encoding used for filenames by the operating system.
`hostname` : | A UTF-8 encoded hostname, or `NULL` for none.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | a newly-allocated string holding the resulting URI, or `NULL` on an error.

### g_locale_from_utf8 ()

    gchar*      g_locale_from_utf8              (const gchar *utf8string,
                                                 gssize len,
                                                 gsize *bytes_read,
                                                 gsize *bytes_written,
                                                 GError **error);

Converts a string from UTF-8 to the encoding used for strings by the C runtime (usually the same as that used by the operating system) in the current locale.

`utf8string` : | a UTF-8 encoded string
`len` : | the length of the string, or -1 if the string is nul-terminated.
`bytes_read` : | location to store the number of bytes in the input string that were successfully converted, or `NULL`. Even if the conversion was successful, this may be less than `len` if there were partial characters at the end of the input. If the error G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value stored will the byte offset after the last valid input sequence.
`bytes_written` : | the number of bytes stored in the output buffer (not including the terminating nul).
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError may occur.
Returns : | The converted string, or `NULL` on an error.

### enum GConvertError

    typedef enum
    {
      G_CONVERT_ERROR_NO_CONVERSION,
      G_CONVERT_ERROR_ILLEGAL_SEQUENCE,
      G_CONVERT_ERROR_FAILED,
      G_CONVERT_ERROR_PARTIAL_INPUT,
      G_CONVERT_ERROR_BAD_URI,
      G_CONVERT_ERROR_NOT_ABSOLUTE_PATH
    } GConvertError;

Error codes returned by character set conversion routines.

`G_CONVERT_ERROR_NO_CONVERSION` | Conversion between the requested character sets is not supported.
`G_CONVERT_ERROR_ILLEGAL_SEQUENCE` | Invalid byte sequence in conversion input.
`G_CONVERT_ERROR_FAILED` | Conversion failed for some reason.
`G_CONVERT_ERROR_PARTIAL_INPUT` | Partial character sequence at end of input.
`G_CONVERT_ERROR_BAD_URI` | URI is invalid.
`G_CONVERT_ERROR_NOT_ABSOLUTE_PATH` | Pathname is not an absolute path.

### g_get_charset ()

    gboolean    g_get_charset                   (G_CONST_RETURN char **charset);

Obtains the character set for the current locale; you might use this character set as an argument to g_convert(), to convert from the current locale's encoding to some other encoding. (Frequently g_locale_to_utf8() and g_locale_from_utf8() are nice shortcuts, though.)

The return value is `TRUE` if the locale's encoding is UTF-8, in that case you can perhaps avoid calling g_convert().

The string returned in `charset` is not allocated, and should not be freed.

`charset` : | return location for character set name
Returns : | `TRUE` if the returned charset is UTF-8

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