PHP: Run function and return values - php

Question

I am trying to run a function that checks a db table for a username and an email. I call the function with two parameters ($user_username, $user_password). The function checks the database to see if those values exist. However, I cannot get the variables from the function to return properly. Here's what i have so far:
Function:
class registerClass{
public function checkUser($user_username, $user_email){
//connect to db via pdo...
$st_1 = $handler->prepare("SELECT * FROM tbl_users WHERE user_username = '$user_username'");
$st_1->execute();
if($st_1->rowCount() > 0){$user_exists = '1';}
$st_2 = $handler->prepare("SELECT * FROM tbl_users WHERE user_email = '$user_email'");
$st_2->execute();
if($st_2->rowCount() > 0){$email_exists = '1';}
}
}
Call to function:
$object = new registerClass();
$object->checkUser($user_username, $user_email);
if($user_exists >= '1'){$errors[] = "Username taken";}
if($email_exists >= '1'){$errors[] = "Email taken";}
For some reason the errors never get thrown. I'm not sure what I'm doing wrong here.

Answer 1

The variables you're setting are local to the function, they're not visible in the scope of the caller. Instead, the function should return the variables in an array:
class registerClass{
public function checkUser($user_username, $user_email){
$user_exists = $email_exists = false;
//connect to db via pdo...
$st_1 = $handler->prepare("SELECT * FROM tbl_users WHERE user_username = '$user_username'");
$st_1->execute();
if($st_1->rowCount() > 0){$user_exists = true;}
$st_2 = $handler->prepare("SELECT * FROM tbl_users WHERE user_email = '$user_email'");
$st_2->execute();
if($st_2->rowCount() > 0){$email_exists = true;}
return array($user_exists, $email_exists)
}
}
You can then use it like this:
list($user_exists, $email_exists) = $object->checkUser($user_username, $user_email);
if($user_exists){$errors[] = "Username taken";}
if($email_exists){$errors[] = "Email taken";}
I've also changed the values from strings with 0 and 1 to booleans false/true.

Answer 2

You should use return to return value by function and than in place where you call your function use for example list to get function return values.
Complete code:
<?php
class registerClass
{
public function checkUser($user_username, $user_email)
{
//connect to db via pdo...
$user_exists = 0;
$email_exists = 0;
$st_1 = $handler->prepare(
"SELECT * FROM tbl_users WHERE user_username = '$user_username'"
);
$st_1->execute();
if ($st_1->rowCount() > 0) {
$user_exists = '1';
}
$st_2 = $handler->prepare(
"SELECT * FROM tbl_users WHERE user_email = '$user_email'"
);
$st_2->execute();
if ($st_2->rowCount() > 0) {
$email_exists = '1';
}
return array($user_exists, $email_exists);
}
}
$object = new registerClass();
list($user_exists, $email_exists) = $object->checkUser(
$user_username,
$user_email
);
if ($user_exists >= '1') {
$errors[] = "Username taken";
}
if ($email_exists >= '1') {
$errors[] = "Email taken";
}
However normally you rather don't set value 1 in that case but boolean true so you should rather use this code:
class registerClass
{
public function checkUser($user_username, $user_email)
{
//connect to db via pdo...
$user_exists = false;
$email_exists = false;
$st_1 = $handler->prepare(
"SELECT * FROM tbl_users WHERE user_username = '$user_username'"
);
$st_1->execute();
if ($st_1->rowCount() > 0) {
$user_exists = true;
}
$st_2 = $handler->prepare(
"SELECT * FROM tbl_users WHERE user_email = '$user_email'"
);
$st_2->execute();
if ($st_2->rowCount() > 0) {
$email_exists = true;
}
return array($user_exists, $email_exists);
}
}
$object = new registerClass();
list($user_exists, $email_exists) = $object->checkUser(
$user_username,
$user_email
);
if ($user_exists) {
$errors[] = "Username taken";
}
if ($email_exists) {
$errors[] = "Email taken";
}

Answer 3

When you call a class method like: $object->checkUser($user_username, $user_email); or a function like : checkUser($user_username, $user_email); you must remember that php pass the params by copy, not by reference.
So by default what you pass (for example $user_name), it's not the same $user_name on function/method body. Seee http://php.net/manual/en/functions.arguments.php for more.
You can resolve your problem by using new method declaration this code:
public function checkUser(&$user_username, &$user_email){
//connect to db via pdo...
$st_1 = $handler->prepare("SELECT * FROM tbl_users WHERE user_username = '$user_username'");
$st_1->execute();
if($st_1->rowCount() > 0){$user_exists = '1';}
$st_2 = $handler->prepare("SELECT * FROM tbl_users WHERE user_email = '$user_email'");
$st_2->execute();
if($st_2->rowCount() > 0){$email_exists = '1';}
}
So to have have an argument to a function passed by reference, prepend an ampersand (&):checkUser(&$user_username, &$user_email)