php 字符串截取，支持中文和其他编码

function.php

//使用方法
$content= mb_substr($content,0,25,'utf-8');

/**
 * 字符串截取，支持中文和其他编码
 * @static
 * @access public
 * @param string $str 需要转换的字符串
 * @param string $start 开始位置
 * @param string $length 截取长度
 * @param string $charset 编码格式
 * @param string $suffix 截断显示字符
 * @return string
 */
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true) {
    if(function_exists("mb_substr"))
        $slice = mb_substr($str, $start, $length, $charset);
    elseif(function_exists('iconv_substr')) {
        $slice = iconv_substr($str,$start,$length,$charset);
        if(false === $slice) {
            $slice = '';
        }
    }else{
        $re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
        $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
        $re['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
        $re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
        preg_match_all($re[$charset], $str, $match);
        $slice = join("",array_slice($match[0], $start, $length));
    }
    return $suffix ? $slice.'...' : $slice;
}

if(!function_exists('array_column')){
    function array_column(array $input, $columnKey, $indexKey = null) {
        $result = array();
        if (null === $indexKey) {
            if (null === $columnKey) {
                $result = array_values($input);
            } else {
                foreach ($input as $row) {
                    $result[] = $row[$columnKey];
                }
            }
        } else {
            if (null === $columnKey) {
                foreach ($input as $row) {
                    $result[$row[$indexKey]] = $row;
                }
            } else {
                foreach ($input as $row) {
                    $result[$row[$indexKey]] = $row[$columnKey];
                }
            }
        }
        return $result;
    }
}