Why is strcmp returning false on the second run?

Question

So right now I'm making a simplistic login system. The client enters the form data and the php handles it by checking a text file that goes like so:

name
pass
name
pass
...so on

The php I'm using to process this is:

$name = $_REQUEST['name'];
$pass = $_REQUEST['pass'];
$validName = false;
$validPass = false;
$pos = 0;

$file_handle = fopen("database.txt", "r");

while (!feof($file_handle)) {

    $line = ltrim( fgets($file_handle), "\n" );

    if ($pos % 2 == 0 ) // Checks for names first on even rows
    {
        if( strcmp( $name, $line))// Normal checking returns correctly
            $validName = true;
    }
    else if( $validName === true ) // if odd, and a matching name check pass
    {
        if( !strcmp( $pass, $line) )// What's going on here? Why is it opposite?
        {
            $validPass = true;
        }
        break;
    }
    $pos++;
}

What's happening is that the first check if( strcmp( $name, $line)) checking if there is a name in the data base that matches the input from the client.

This correctly returns true when the clients name matches a name in the data base. I check the password the EXACT same way, but some how it returns false when it's suppose to be true, and returns true when it's suppose to be false.

What's going on here?

On a side note, I'm only using strcmp because I couldn't get $name === $line to work.

Answer 1

strcmp() returns an integer, not a boolean. In fact, it returns 0 if the strings match, which would evaluate to false in an if-statement. That is why it appears to have "reverse" behavior compared to a typical boolean function.

See the documentation.