PHP中的字符串比较[重复]

So i have been trying to compare two strings. One from a $_POST method , and one read from a text file. Although they seem to be the same when I print both of them, my strcmp() never returns 0 meaning that they are not equal. Why does my strcmp() function never return 0?

Here is the actual code :

$fileRead = 'Users.txt';
$wasRead = FALSE;
$handleRead = fopen($fileRead,'r');
$character = fread($handleRead,1);
echo"<p> ".$character." </p>";
fgets($handleRead);

while($character != 'Q')
{
    $lineName = fgets($handleRead);
    echo "<p> ".$lineName." </p>";

    $linePassword = fgets($handleRead);
    echo "<p> ".$linePassword." </p>";

    $character = fread($handleRead,1);
    echo"<p> ".$character." </p>";
    fgets($handleRead); 

    $porfavor = $_POST['newUserId'];
    $porfavor = strtolower($porfavor);

    echo $porfavor."<br>";
    echo $lineName."<br>";

    //$comparison = strcmp($lineName." ",$_POST['newUserId']);
    //echo $comparison;

    $comparison = strcmp($porfavor,$lineName);
    echo $comparison;

    if($comparison == 0)
    {
        $character = 'Q';
        echo  "<p> User Already Exists </p>";
        echo "<a href = \" newUser.html\"> Sing In</a>";
        echo "<br>";
    }

}


fclose($handleRead);

</div>

You may have an invisible character in one of your strings. Try doing a var dump.

$comparison = strcmp($porfavor,$lineName);
if($comparison != 0){
echo "<pre>";
var_dump($porfavor);
var_dump($lineName);
exit;
}

some tips:

1. You may need to use trim() on your variables to account for whitespace;
2. consider using strtoupper() if either might vary in case. Keep in mind it's case sensitive.