Form validation in php error in validate() function

Question

In this code, I cannot match the regular expressions in validate() function help me where I was wrong

I entered data in the user input other than alphabets like (john1246@##$##@+-) it returns the input value (john1246@##$##@+-) or $data in validate() function but not showing the error which should return PRG_MTH_ERR. what is the problem in my code?

validate.php

function validate($data, $reg_exp = "") {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    if (empty($data) == true) {
        return "EMT_FLD";
    } elseif ($data != preg_match($reg_exp,$data)) {
        return "PRG_MTH_ERR";
    } else {
        return $data;
     }
}

login.php

if (isset($_POST['login'])) {
     include "./database/db.php";
     $db = new db();
     include 'validate.php';

     echo validate($_POST['user'],"/^['a-zA-z']$/");
}

I expected that it returns PRG_MTH_ERR but it returns $data

Chocorean · Accepted Answer · 2019-05-16 07:33:20Z

2

Loose comparison is your issue :

elseif ($data != preg_match($reg_exp,$data)) {

Because "john1246@##$##@+-" == 0 is true.

You might compare 1 to the result of preg_match (see the doc to learn more about preg_match)

edited May 16, 2019 at 7:33

answered May 16, 2019 at 7:29

Chocorean

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1 Comment

Chocorean Over a year ago

And btw, Igor is right, you have a mistake in your regex

GabrieleMartini · Accepted Answer · 2019-05-16 07:28:56Z

2

preg_match() returns 1 if the pattern matches given subject, 0 if it does not, or FALSE if an error occurred.

In your code,

$data

is never returned by

preg_match($reg_exp,$data)

answered May 16, 2019 at 7:28

GabrieleMartini

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Comments

Igor Melekhov · Accepted Answer · 2019-05-16 07:30:10Z

2

Change

$data != preg_match($reg_exp,$data)

to

1 != preg_match($reg_exp,$data)

and regexp to /^[a-zA-Z]*$/

answered May 16, 2019 at 7:30

Igor Melekhov

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Brain Developer · Accepted Answer · 2019-05-16 07:35:39Z

2

The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.

So just use }elseif (preg_match($reg_exp,$data)) { instead of }elseif ($data != preg_match($reg_exp,$data)) {

Hope it will help.

answered May 16, 2019 at 7:35

Brain Developer

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