php隐藏手机号中间四位的方法

$num = "13966778888"
$str = substr_replace($num,'****',3,4);

//自定义函数手机号隐藏中间四位
function yc_phone($str){
    $str=$str;
    $resstr=substr_replace($str,'****',3,4);
    return $resstr;
}

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