PHP verifies that the user name starts with a letter and validates the password instance _php tutorial

PHP verifies that the user name starts with a letter and validates the password instance

This article describes how PHP verifies that a user name begins with a letter and validates the password. Share to everyone for your reference. Specific as follows:

Verify that the user name starts with a letter and that the authentication password is only a combination of numbers and letters, three common validation functions: Verify the Mailbox address format, verify that the password is only a combination of numbers and letters, and verify that the user name starts with a letter, which is used when the user registers or submits the form.

The code is as follows:

function Is_email ($email)
{
if (Preg_match ("/[a-za-z0-9]+@[a-za-z0-9]+.[ a-z]{2,4}/", $email, $mail))
{
return true;
}
Else
{
return false;
}
}

/**
* Verify that the user name starts with a letter
*/

function Is_user_name ($user)
{
if (Preg_match ("/^[a-za-z]{1}" ([a-za-z0-9]|[. _]) {3,19}$/", $user, $username))
{
return true;
}
Else
{
return false;
}
}

/**
* Verify that the password is only a combination of numbers and letters
*/

function is_psd ($PSD)
{
if (Preg_match ("/^ (w) {4,20}$/", $PSD, $password))
{
return true;
}
Else
{
return false;
}
}

I hope this article is helpful to everyone's regular expression learning.

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