Parameters and arguments in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of function with default parameter

What is the output of this PHP code?

PHP

<?php
function greet($name = "Guest") {
    echo "Hello, $name!";
}
greet();
?>

A Syntax error

B Hello, !

C Hello, $name!

D Hello, Guest!

💡 Hint

Check what happens when no argument is passed to a function with a default parameter.

The function greet has a default parameter value 'Guest'. When called without arguments, it uses this default and prints 'Hello, Guest!'.

❓ Predict Output

intermediate

Output with passed argument overriding default

What will this PHP code output?

PHP

<?php
function multiply($a, $b = 2) {
    return $a * $b;
}
echo multiply(5, 3);
?>

A 6

B 15

C 10

D Error: Missing argument

💡 Hint

The second argument is provided, so default is ignored.

The function multiply multiplies $a and $b. Here, $a=5 and $b=3 (passed), so output is 15.

❓ Predict Output

advanced

Output of function with reference parameter

What is the output of this PHP code?

PHP

<?php
function addOne(&$num) {
    $num += 1;
}
$value = 10;
addOne($value);
echo $value;
?>

A 11

B 10

C 1

D Error: Cannot pass by reference

💡 Hint

The function parameter is passed by reference, so changes affect the original variable.

The function addOne increases the value of $num by 1. Since $num is passed by reference, $value changes from 10 to 11.

❓ Predict Output

advanced

Output of function with variable-length argument list

What will this PHP code output?

PHP

<?php
function sumAll(...$numbers) {
    return array_sum($numbers);
}
echo sumAll(1, 2, 3, 4);
?>

A 10

B 1,2,3,4

C Array

D Error: Unexpected ... operator

💡 Hint

The function uses a variable-length argument list to sum all numbers.

The function sumAll collects all arguments into an array and sums them. 1+2+3+4=10.

🧠 Conceptual

expert

Identify the error in function call with missing argument

What error will this PHP code produce?

PHP

<?php
function divide($x, $y) {
    return $x / $y;
}
echo divide(10);
?>

A Warning: Missing argument for parameter 2

B Output: 10

C Fatal error: Uncaught ArgumentCountError

D No error, outputs 0

💡 Hint

PHP 7+ throws a specific error when required arguments are missing.

Calling divide with only one argument causes a fatal ArgumentCountError because the second required parameter is missing.