PHP 截取字符串专题

PHP 截取字符串专题
作者: 不详 来源: 不详

1. 截取GB2312中文字符串
<?php
//截取中文字符串
function mysubstr($str, $start, $len) {
    $tmpstr = "";
    $strlen = $start + $len;
    for($i = 0; $i < $strlen; $i++) {
        if(ord(substr($str, $i, 1)) > 0xa0) {
            $tmpstr .= substr($str, $i, 2);
            $i++;
        } else
            $tmpstr .= substr($str, $i, 1);
    }
    return $tmpstr;
}
?>

2. 截取utf8编码的多字节字符串
<?php
//截取utf8字符串
function utf8Substr($str, $from, $len)
{
    return preg_replace(''#^(?:[x00-x7F]|[xC0-xFF][x80-xBF]+){0,''.$from.''}''.
                       ''((?:[x00-x7F]|[xC0-xFF][x80-xBF]+){0,''.$len.''}).*#s'',
                       ''$1'',$str);
}
?>

3. UTF-8、GB2312都支持的汉字截取函数
<?php
/*
Utf-8、gb2312都支持的汉字截取函数
cut_str(字符串, 截取长度, 开始长度, 编码);
编码默认为 utf-8
开始长度默认为 0
*/
 
function cut_str($string, $sublen, $start = 0, $code = ''UTF-8'')
{
    if($code == ''UTF-8'')
    {
        $pa = "/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]|xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/";
        preg_match_all($pa, $string, $t_string);
 
        if(count($t_string[0]) - $start > $sublen) return join('''', array_slice($t_string[0], $start, $sublen))."...";
        return join('''',