使用php验证txt文件中是否已存在给定的用户名

Question

I have an assignment where i need to create a register page and verify if a user doesn't exist already in a txt file. I found some answers online and tried to apply them but doesn't seem to work for me. everything works except the part that he needs to verify. here is my code: this is my code

<?php
if($_POST['formSubmit'] == "Submit")
{
    $errorMessage ="";
    $link_Create = "CreateAnAccount.php";
    $Username = $_POST['userName'];
    $password = $_POST['Password'];

    if(empty($_POST['userName']))
    {
        echo "<li>You forget to enter a UserName</li><a href='".$link_Create."'>Start again</a>";
        header("Location:PopUp.html");
        exit;
    }

    if(empty($_POST['Password']))
    {
        echo "<li>You forget to enter a Password</li><a href='".$link_Create."'>Start again</a>";
        header("Location:PopUp.html");
        exit;
    }
    if(!preg_match('/^(?=.*\d)(?=.*[A-Za-z])[0-9A-Za-z!@#$%]{4,24}$/', $password))
    {
        echo "<li>Your Password input was wrong, please notice Paswword most be at least 4 characters long, have at least one letter and at least one digit. </li><a href='".$link_Create."'>Start again</a>";
        header("Location:PopUp.html");
        exit;
    }

    if(empty($errorMessage)){
        $userlist = fopen("login.txt","r");
        $success = true;
        foreach ($userlist as $user) {
            $user_details = explode('|', $user);
            if ($user_details[0] == $Username) {
                $success = false;
                break;
            }
        }

        fclose($userlist);
        if ($success==true) {
            $writer = fopen("login.txt", "a") or die("Unable to open file.");
            fwrite($writer,$Username."|");
            fwrite($writer,$password."
");
            fclose($writer);

            echo "<br>You have been logged in. <br>";
            header("Location:PopUp.html");
            exit;
        }
        else {
            echo "<li>This User Name already exist!</li><a href='".$link_Create."'>Start again</a>";
            header("Location:PopUp.html");
            exit;
        }
    }
}
?>

Let me know if there is the need of my html code but i don't think it has any effect on the issue. Thank you very much I appreciate the help.

Answer 1

You have problem with iterating over resource which return fopen function

$userlist = fopen("login.txt","r");
$success = true;
foreach ($userlist as $user) {
    $user_details = explode('|', $user);
    if ($user_details[0] == $Username) {
        $success = false;
        break;
    }
}

Try to replace it with this iterating over each line of userlist file:

$file = new \SplFileObject("login.txt");
// Loop until we reach the end of the file
while (!$file->eof()) {
    $user = $file->fgets();
    $user_details = explode('|', $user);
    if ($user_details[0] == $Username) {
        $success = false;
        break;
    }
}