这个正则表达式是什么意思/^.*(?=.{4,5})(?=.*[az])(?=.*[AZ])(?=.* [0-9]）。 * $ / [重复]

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• Reference - What does this regex mean? 1 answer

Can someone elaborate the following regular expression:

if($pass == $re_pass) {
    //password validation
    $pattern_up = "/^.*(?=.{4,56})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9]).*$/";

    if(!preg_match($pattern_up, $pass)) {
        $errPass = "Must be at lest 4 character long, 1 upper case, 1 lower case letter and 1 number exist";
    }
}

what I want to achieve is to check the entered password is between the number of 4 and 56. I already specified it in the code. However, when I tried, it can accept more than that range.

My question, is how i can specify the upper limit, i dont want to exceed 56 characters long. And if you can elaborate it more, so i can understand it more. this code is not made by me.

Thanks,

I am trying to do sign up page in php

if($pass == $re_pass) {
    //password validation
    $pattern_up = "/^.*(?=.{4,56})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9]).*$/";

    if(!preg_match($pattern_up, $pass)) {
        $errPass = "Must be at lest 4 character long, 1 upper case, 1 lower case letter and 1 number exist";
    }
}

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Answer 1

Just use anchors: ^.{4,56}$

^ - match beginning of a string

$ - match end of a string

.{4,56} - match any character at least 4 and at most 56 times

Demo

You can use it in positive lookahead: (?=^.{4,56}$)