Recursive PHP function is not returning expected value
I am trying to create a function that will create a unique username for each user stored in the database.
My plan was to create a username by concatenating the first and last name then check if this username was taken. If it wasn't just store it in the database and if it was then add a number on the end of it.
For example if ConnorAtherton was taken the function would next check ConnorAtherton1, ConnorAtherton2 until it found a unique username.
Here is the function (I have added some echo statements for debugging)
function createUserName($username, $counter){
global $fname, $lname;
echo "\t\t\tUsername at Start - " . $username . "\n";
// connect to database
require($_SERVER['DOCUMENT_ROOT'] . "/inc/db.connect.php");
$stmt = $conn->prepare('SELECT * FROM users WHERE username = ?');
$stmt->bind_param('s', $username);
$stmt->execute();
$stmt->store_result();
echo "\t\t\tUsername before loop - " . $username . "\n";
if( $stmt->num_rows > 0){
//construct original name and try again
$username = ucfirst($fname) . ucfirst($lname) . $counter;
$counter++;
createUserName($username, $counter);
}
echo "\t\t\tUsername after loop - " . $username . "\n\n";
return $username;
}
Here is what it returns to the console
Username at Start - ConnorAtherton
Username before loop - ConnorAtherton
Username at Start - ConnorAtherton1
Username before loop - ConnorAtherton1
Username at Start - ConnorAtherton2
Username before loop - ConnorAtherton2
Username after loop - ConnorAtherton2
Username after loop - ConnorAtherton1
It returns the correct value after the loop (ConnorAtherton2) to begin with but I don't know why there would be a second value after the loop.
It returns ConnorAtherton1 and I need it to return ConnorAtherton2.
Any help is greatly appreciated.
Answer
Solution:
The code executes as expected. What you are seeing is just the stack unwinding from the recursive calls.
You should modify your function to exit after the recursive call, by returning the result from the recursive call
Answer
Solution:
You can achieve what you want without recursion much easier. The basic logic would look like this:
You'd only have to implement the
doesNameExist()method. There you do the DB query and returntrueif the name already exists.The
($counter++)part will append an empty string on first iteration (the++suffix increases the variable after the value was evaluated).