PHP 手册
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# CXLII. String 字符串处理函数

# 简介

本类函数用来对字符串进行各种操作。对字符串的一些其它专门操作，可以参考手册的正则表达式部分和 URL 操作部分。

如果想要了解字符串的相关内容，特别是有关单引号，双引号等的处理部分，可以参考手册中类型部分中的字符串条目。

# 需求

要编译本扩展模块不需要外部库文件。

# 安装

本函数库作为 PHP 内核的一部分，不用安装就能使用。

# 预定义常量

以下常量由本扩展模块定义，因此只有在本扩展模块被编译到 PHP 中，或者在运行时被动态加载后才有效。

`CRYPT_SALT_LENGTH` integer

`CRYPT_STD_DES` integer

`CRYPT_EXT_DES` integer

`CRYPT_MD5` integer

`CRYPT_BLOWFISH` integer

`HTML_SPECIALCHARS` (integer)

`HTML_ENTITIES` (integer)

`ENT_COMPAT` (integer)

`ENT_QUOTES` (integer)

`ENT_NOQUOTES` (integer)

`CHAR_MAX` (integer)

`LC_CTYPE` (integer)

`LC_NUMERIC` (integer)

`LC_TIME` (integer)

`LC_COLLATE` (integer)

`LC_MONETARY` (integer)

`LC_ALL` (integer)

`LC_MESSAGES` (integer)

`STR_PAD_LEFT` (integer)

`STR_PAD_RIGHT` (integer)

`STR_PAD_BOTH` (integer)

# 参见

如果想更深入的了解有关字符串高级操作的相关内容，请参阅手册的 POSIX 扩展正则表达式函数和 Perl 兼容正则表达式函数部分。

目录
addcslashes -- 像 C 那样使用反斜线转义字符串中的字符
addslashes -- 使用反斜线引用字符串
bin2hex -- 将二进制数据转换成十六进制表示
chop -- rtrim() 的别名函数
chr -- 返回指定的字符
chunk_split -- 将字符串分割成小块
convert_cyr_string -- 将字符由一种 Cyrillic 字符转换成另一种
convert_uudecode -- Decode a uuencoded string
convert_uuencode -- Uuencode a string
count_chars -- 返回字符串所用字符的信息
crc32 -- 计算一个字符串的 crc32 多项式
crypt -- One-way string encryption (hashing)
echo -- Output one or more strings
explode -- 使用一个字符串分割另一个字符串
fprintf -- Write a formatted string to a stream
get_html_translation_table -- Returns the translation table used by htmlspecialchars() and htmlentities()
hebrev -- Convert logical Hebrew text to visual text
hebrevc -- Convert logical Hebrew text to visual text with newline conversion
html_entity_decode -- Convert all HTML entities to their applicable characters
htmlentities -- Convert all applicable characters to HTML entities
htmlspecialchars_decode -- Convert special HTML entities back to characters
htmlspecialchars -- Convert special characters to HTML entities
implode -- Join array elements with a string
join -- 别名 implode()
levenshtein -- Calculate Levenshtein distance between two strings
localeconv -- Get numeric formatting information
ltrim -- Strip whitespace (or other characters) from the beginning of a string
md5_file -- Calculates the md5 hash of a given file
md5 -- Calculate the md5 hash of a string
metaphone -- Calculate the metaphone key of a string
money_format -- Formats a number as a currency string
nl_langinfo -- Query language and locale information
nl2br -- Inserts HTML line breaks before all newlines in a string
number_format -- Format a number with grouped thousands
ord -- Return ASCII value of character
parse_str -- Parses the string into variables
print -- Output a string
printf -- Output a formatted string
quoted_printable_decode -- Convert a quoted-printable string to an 8 bit string
quotemeta -- Quote meta characters
rtrim -- Strip whitespace (or other characters) from the end of a string
setlocale -- Set locale information
sha1_file -- Calculate the sha1 hash of a file
sha1 -- Calculate the sha1 hash of a string
similar_text -- Calculate the similarity between two strings
soundex -- Calculate the soundex key of a string
sprintf -- Return a formatted string
sscanf -- Parses input from a string according to a format
str_ireplace -- Case-insensitive version of str_replace().
str_pad -- Pad a string to a certain length with another string
str_repeat -- Repeat a string
str_replace -- Replace all occurrences of the search string with the replacement string
str_rot13 -- Perform the rot13 transform on a string
str_shuffle -- Randomly shuffles a string
str_split -- Convert a string to an array
str_word_count -- Return information about words used in a string
strcasecmp -- Binary safe case-insensitive string comparison
strchr -- 别名 strstr()
strcmp -- Binary safe string comparison
strcoll -- Locale based string comparison
strcspn -- Find length of initial segment not matching mask
strip_tags -- Strip HTML and PHP tags from a string
stripcslashes -- Un-quote string quoted with addcslashes()
stripos -- Find position of first occurrence of a case-insensitive string
stripslashes -- Un-quote string quoted with addslashes()
stristr -- Case-insensitive strstr()
strlen -- Get string length
strnatcasecmp -- Case insensitive string comparisons using a "natural order" algorithm
strnatcmp -- String comparisons using a "natural order" algorithm
strncasecmp -- Binary safe case-insensitive string comparison of the first n characters
strncmp -- Binary safe string comparison of the first n characters
strpbrk -- Search a string for any of a set of characters
strpos -- Find position of first occurrence of a string
strrchr -- Find the last occurrence of a character in a string
strrev -- Reverse a string
strripos -- Find position of last occurrence of a case-insensitive string in a string
strrpos -- Find position of last occurrence of a char in a string
strspn -- Find length of initial segment matching mask
strstr -- Find first occurrence of a string
strtok -- Tokenize string
strtolower -- Make a string lowercase
strtoupper -- Make a string uppercase
strtr -- Translate certain characters
substr_compare -- Binary safe optionally case insensitive comparison of 2 strings from an offset, up to length characters
substr_count -- Count the number of substring occurrences
substr_replace -- Replace text within a portion of a string
substr -- Return part of a string
trim -- Strip whitespace (or other characters) from the beginning and end of a string
ucfirst -- Make a string's first character uppercase
ucwords -- Uppercase the first character of each word in a string
vfprintf -- Write a formatted string to a stream
vprintf -- Output a formatted string
vsprintf -- Return a formatted string
wordwrap -- Wraps a string to a given number of characters using a string break character

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