截取文字中间的字符串，下面是截取淘宝分享的示例

<?php

 
 

 $str='fu植这行话¢6IHS1SnNJei¢转移至τáǒЬáǒ，【这个#聚划算团购#宝贝不错:电脑桌台式家用办公桌子卧室书桌简约现代写字桌学生学习桌经济型(分享自@手机淘宝android客户端)】';
  $str='电脑桌台式家用办公桌子卧室书桌简约现代写字桌学生学习桌经济';
  $str='付致这行话$pH1H1SnnFZW$转移至淘宀┡ē【电脑桌台式家用办公桌子卧室书桌简约现代写字桌学生学习桌经济型】；或https://m.tb.cn/h.V4CepUy?sm=f1ebc0 掂击鏈→接，再选择瀏lan嘂..大开';
if(strstr($str, '【')&&strstr($str, '】')){
   
    $t1 = mb_strpos($str,'【')+3;
    $t2 = mb_strpos($str,'】');
    $s = mb_substr($str,$t1,$t2-$t1);
    if(strstr($s, ':')){
        $t3 = mb_strpos($s,':')+1;
         $s = mb_substr($s,$t3);
    }
    if(strstr($s, '(')){
        $t4 = mb_strpos($s,'(');
        $s = mb_substr($s,0,$t4);
    }

}else{
    $s=$str;
}
echo $s;

下面是改编的函数

if (!function_exists('jiezhong') ){
 function jiezhong($str,$ss,$es)
    {
        if(strstr($str, $ss)&&strstr($str, $es)){
           
            $t1 = mb_strpos($str,$ss);
            $t2 = mb_strpos($str,$es);
            $s = mb_substr($str,$t1,$t2);
            
        
        }else{
            $s=$str;
        }
        return $s; 
    }
}