使用函数和PDO检查帐户是否存在

Question

I am having some trouble using functions to check if user account already exist in the backend. I created two functions: one to check if user account already exist and the other to create account.

Can someone enlighten me...? What is wrong with the code here?

<?php

    try{
    $username = 'web';
    $password = '1234';
    $username_signup = $_POST['username_signup'];
    $password_signup = $_POST['password_signup'];
    $hash = crypt($_POST['password'], '$3a$08$2'); // salt 

    $connection = new PDO ('mysql:host=localhost;dbname=tongue', $username, $password);
    $connection -> setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $connection -> setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

    function check(c){
    $statement = $connection->prepare('
        SELECT email FROM user
        WHERE email=:username;
        ');
    $statement -> bindParam(':username', c, PDO::PARAM_STR, 127);
    $check = $statement -> execute();
    return $check;
    };

    function create(a,b){
    $statement = $connection->prepare('
        INSERT INTO user (email, hash)
        VALUES (:username, :hash);
        ');
    $statement -> bindParam(':username', a, PDO::PARAM_STR, 127);
    $statement -> bindParam(':hash', b, PDO::PARAM_STR);
    $statement -> execute();
    }

    check($username_signup);

    if ($check==0){
        create($username_signup, $hash);
        header("Location=index.php");
        exit();
    } else {
        header("Location=sign_up.php?error=1");
        exit();
    }


    $connection = null; 
    } // try{}

    catch(PDOException $e) {
        echo $e->getMessage();
        }   

?>

Answer 1

$connection is not global so it is not set inside the functions so you either need to make it global (don't) or pass it in as a argument

p.s. you should really work on your functions and variables names