Function to validate username and password not working [duplicate] - php

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Closed 10 years ago.
Possible Duplicate:
Regular Expression matching for entire string
On my form page, I am trying to make it only accept alphanumeric characters for my username and password and require that they be from 6 to 15 characters. When I type in invalid data, it will insert it into the database rather than throw the user error that I defined in my CheckAlNum function.
functions.php
function checkAlNum($whichField)
{
if (preg_match('/[A-Za-z0-9]+/', $_POST[$whichField])){
if ( (!count(strlen($whichField) >= 6)) OR (!count(strlen($whichField) <= 15 ))) {
$message1 = '<p> Username and password must be between 6 and 15 characters </p>';
return user_error($message1);
}
else{
return true;
}
}
else {
$message = '<p>Username and password can only be numbers or letters</p>';
return user_error($message);
}
}
Form.php
if (count($_POST) > 0) {
//Validate the inputs
$errorMessages = array();
//Validate the username
$item5 = checkAlNum('username');
if($item5 !== true) {
$errorMessages[] = $item5;
}
//Validate the password
$item6 = checkAlNum('password');
if($item6 !== true) {
$errorMessages[] = $item6;
}
//Validate the firstName and lastName
$item1 = checkNameChars('firstName');
if ($item1 !== true) {
$errorMessages[] = $item1;
}
$item2 = checkNameChars('lastName');
if ($item2 !== true) {
$errorMessages[] = $item2;
}
//Validate the office name
$item3 = checkOfficeChars('office');
if ($item3 !== true) {
$errorMessages[] = $item3;
}
//Validate the phone number
$item4 = validate_phone_number('phoneNumber');
if($item4 !== true) {
$errorMessages[] = $item4;
}
//Check to see if anything failed
if (count($errorMessages) == 0) {
$newEmployee = new Person;
$newEmployee -> insert();
}
else { //Else, reprint the form along with some error messages
echo "<h2><span>Error</span>: </h2>";
foreach($errorMessages as $msg) {
echo "<p>" . $msg . "</p>";
}
}
}
?>
I've tried playing around with the nesting of the if-else statements of the checkAlNum function and also the regex (although I'm pretty sure the regex is right). Maybe I'm just missing something really silly?

Answer 1

function checkAlNum($whichField)
{
if (preg_match('/^[a-z0-9]{6,15}$/i', $_POST[$whichField])) {
return true;
}
else {
$message = '<p>Username and password can only be numbers or letters, 6-15 characters long</p>';
return user_error($message);
}
}
Without the ^ and $ anchors, your regex only checks whether there are alphanumerics anywhere in the field, not that the whole thing is alphanumeric. And changing + to {6,15} implements the length check here, so you can remove that extra check in your code.

Answer 2

I think the second if statement is incorrect. It should be like this:
if ( !( (!count(strlen($whichField) >= 6)) OR (!count(strlen($whichField) <= 15 )) ) ) {
// ... do something
}
This is due to De Morgan Rule which states
A AND B = !( !A OR !B )
In any case, I would not do my checks this way, strucurally you will end up with too many nested if statements that are hard to maintain and make your code look unpretty. Try avoiding nested conditions in your code.

Answer 3

Barmar's answer is the best. But if you want to keep your if statement to check string length, you need to remove the count() as you are already checking the length using strlen().
if ( (!(strlen($whichField) >= 6)) OR (!(strlen($whichField) <= 15 ))) {