How to compare two string fields in PHP

Question

I am a login/register page and I have this for my login:

session_start();

$username = $_POST["username"];
$password = $_POST["password"];

$user_infile = "";
$password_infile = "";

$user_data = fopen("user_data.txt", "r");

while(! feof($user_data)){
    $userArray = fgetcsv($user_data);

    if ($userArray[0] == $username){
        $user_infile = $userArray[0];
        $password_infile = $userArray[1];
    }
    
}

if (strval($password)  ==  strval($password_infile)){
    $_SESSION["loggedin"] = true;
    $_SESSION["username"] = $username;
    $_SESSION["password"] = $password;
    header('Location: home.php');
    exit();
}
else{
    header('Location: error.php');  
    exit();
}

The login works perfect if the password is numeric i.e 123, but if password contains characters ie abc, the comparison fails and the else statement is executed. I used strval to convert both to string, but didnt work. I simply used password == password, that didnt work too. strcmp also didnt work. Am I missing something here?

Edit: This is the input file:

new, 123, 0
admin, pass, 0
jon, a1, 0

As everything that come to you via $_POST is a string, why are you using strval() — RiggsFolly
– RiggsFolly, Commented Nov 5, 2020 at 15:38
Side note: use a break; after you find the user to avoid iterate through all the file after you find the user — Felippe Duarte
– Felippe Duarte, Commented Nov 5, 2020 at 15:39
var_dump($password, $password_infile); to see what's different. — Felippe Duarte
– Felippe Duarte, Commented Nov 5, 2020 at 15:42

Technoh · Accepted Answer · 2020-11-05 15:48:49Z

1

You should add quotes around your text field to be sure that fgetcsv reads it all, then modify the fgetcsv to include the character used as a text delimiter. In general CSV files should not contain extra spaces around the delimiter as these can be interpreted as being part of a field. Make sure you remove all spaces that are not part of the fields. You should also remove the strval calls and simply compare the two values.

"new","123",0
"admin","pass",0
"jon","a1",0

$userArray = fgetcsv($user_data, 0, ',', '"');

if ($password == $password_infile) { // etc.

answered Nov 5, 2020 at 15:48

Technoh

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