> * 分割字符() `array explode ( string $delimiter , string $string [, int $limit ] )` > * base64编码() `string base64_encode ( string $data )` > * base64_decode() `string base64_decode ( string $data [, bool $strict = false ] )` > * 字符替换() `mixed str_replace ( mixed $search , mixed $replace , mixed $subject [, int &$count ] )` > * 反转字符() `string strrev ( string $string )` > * 取首次出现位置() `int strrpos ( string $haystack , string $needle [, int $offset = 0 ] )` > * 转大写() `string strtoupper ( string $string )` > * 转小写() `string strtolower ( string $str )` > * 移除字符尾部() `string rtrim ( string $str [, string $charlist ] )` > * 移除字符头部() `string ltrim ( string $str [, string $charlist ] )` > * 移除首尾字符() `string trim ( string $str [, string $charlist = " \t\n\r\0\x0B" ] )` > * 到时间戳() `int strtotime ( string $time [, int $now = time() ] )` > * json编码() `string json_encode ( mixed $value [, int $options = 0 ] )` > * json解码() `mixed json_decode ( string $json [, bool $assoc = false [, int $depth = 512 [, int $options = 0 ]]] )` > * url编码() `string urlencode ( string $str )` > * url解码() `string urldecode ( string $str )` > * 取字符长度() `int strlen ( string $string )` > * 过滤HTML字符() `string htmlspecialchars ( string $string [, int $flags = ENT_COMPAT | ENT_HTML401 [, string $encoding = 'UTF-8' [, bool $double_encode = true ]]] )` > * 打乱字符() `string str_shuffle ( string $str )` > * 字符转数组() `array str_split ( string $string [, int $split_length = 1 ] )` > * 替换字符() `mixed str_replace ( mixed $search , mixed $replace , mixed $subject [, int &$count ] )` > * 截取字符() `string substr ( string $string , int $start [, int $length ] )` > * 截取中文字符() `string mb_substr ( string $str , int $start [, int $length = NULL [, string $encoding = mb_internal_encoding() ]] )` > * 取中文字符长度() `mixed mb_strlen ( string $str [, string $encoding = mb_internal_encoding() ] )` > * 取字符首次位置() `string strstr ( string $haystack , mixed $needle [, bool $before_needle = false ] )` > * 查找字符() `string strpbrk ( string $haystack , string $char_list )` > * 字符出现次数() `int substr_count ( string $haystack , string $needle [, int $offset = 0 [, int $length ]] )` > * 中文字符出现次数() `int mb_substr_count ( string $haystack , string $needle [, string $encoding = mb_internal_encoding() ] )`