Show DIV in other .php file only when php statement is true - php

Question

quick question. I'm a rookie so,
when registration success I want to show <div> with a message(value).
So if everything is alright only then should appear on another .php file with HTML code.
I tried to return it but cannot figure out how to do it in the right way.
NOTE:
Now I'm using global but I want to throw it out.
So I have a function in function.php and if...
function createUser(){
global $welcome;
$connection = connectDB();
$username = $_POST['username'];
$email = $_POST['email'];
$password = $_POST['password'];
$passwordConfirm = $_POST["passwordConfirm"];
$username = mysqli_real_escape_string($connection, $username);
$email = mysqli_real_escape_string($connection, $email);
$password = mysqli_real_escape_string($connection, $password);
$passwordConfirm = mysqli_real_escape_string($connection, $passwordConfirm);
if($_POST['password'] !== $_POST['passwordConfirm']){
$error = exit("Password does not match.");
}
$hashFormat = "$2y$10$";
$salt = "iusesomecrazystrings22";
$hash = $hashFormat . $salt;
$password = crypt($password, $hash);
$query = "INSERT INTO users(username, email, password) VALUES ('$username', '$email', '$password')";
$result = mysqli_query($connection, $query);
if(!$result){
die("Query FAILED " . mysqli_error($connection));
} else{
$welcome = "Registration Success";
}
}
And in other file I have something like this:
<?php
include 'functions.php';
global $welcome;
if(isset($_POST['submit'])){
createUser();
}
?>
<div class="row justify-content-md-center">
<form action="register.php" method="post">
<div class="form-group">
<input type="text" name="username" class="form-control" placeholder="Username" style="text-align: center" required>
</div>
<div class="form-group">
<input type="email" name="email" class="form-control" placeholder="Email" style="text-align: center" required>
</div>
<div class="form-group">
<input type="password" name="password" class="form-control" placeholder="Password" style="text-align: center" required>
</div>
<div class="form-group">
<input type="password" name="passwordConfirm" class="form-control" placeholder="Confirm Password" style="text-align: center" required>
</div>
<div class="row justify-content-md-center">
<input type="submit" name="submit" value="SIGN UP" class="btn btn-primary">
</div>
<p></p>
<div class="row justify-content-md-center">
<?php echo $welcome; ?>
</div>
</form>
</div>
So I did it this way...
How should I return instead of $welcome = "Registration Success";, show it ONLY if $result is true and finally print that message in other file that contains HTML.

Answer 1

You can return $message from the function and receive it like this:
if(isset($_POST['submit'])){
$message = createUser();
}
and modify your function createUser like this:
UPDATED
function createUser()
{
// here is your function's body))))
if ($result) {
return "Registration Success";
}
die("Query FAILED " . mysqli_error($connection));
}

Answer 2

if I understand properly:
In createUser(), instead of:
if(!$result){
die("Query FAILED " . mysqli_error($connection));
} else{
$welcome = "Registration Success";
}
Do this:
if(!$result){
die("Query FAILED " . mysqli_error($connection));
}
return true;
And in the PHP file with the HTML do this:
<?php
include 'functions.php';
$userCreated = false;
if(isset($_POST['submit'])){
$userCreated = createUser();
}
if ($userCreated) { ?>
Here goes your message about successfull user creation, or you can use echo '' and you can skip PHP open close tag
<?php } else { ?>
<div class="row justify-content-md-center">
<form action="register.php" method="post">
...
</form>
</div>
<?php }
?>
With this you dont need to use global, instead you use createUser function's return value, which tells you wheter it was successfull or not.