php隐藏手机号中间四位的方法

$num = "12345678910"
$str = substr_replace($num,'****',3,4);

<?php
$tel = '12345678910';
//1.字符串截取法
$new_tel1 = substr($tel, 0, 3).'****'.substr($tel, 7);
var_dump($new_tel1);
//2.替换字符串的子串
$new_tel2 = substr_replace($tel, '****', 3, 4);
var_dump($new_tel2);
//3.用正则
$new_tel3 = preg_replace('/(\d{3})\d{4}(\d{4})/', '$1****$2', $tel);
var_dump($new_tel3);
?>
结果：

> string(11) "123****8910"
> string(11) "123****8910"
> string(11) "123****8910"