Function declaration and calling in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a function with default parameter

What is the output of this PHP code?

PHP

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

A Hello, name!

B Hello, !

C Hello, Guest!

D Syntax Error

💡 Hint

Check the default value of the parameter in the function.

The function greet has a default parameter 'Guest'. When called without arguments, it returns 'Hello, Guest!'.

❓ Predict Output

intermediate

Return value from a function call

What will be the output of this PHP code?

PHP

<?php
function add($a, $b) {
    return $a + $b;
}
$result = add(5, 3);
echo $result;
?>

A 5 + 3

B 53

C Error: Undefined function

D 8

💡 Hint

The function returns the sum of two numbers.

The function add returns the sum of 5 and 3, which is 8.

🔧 Debug

advanced

Identify the error in function call

What error will this PHP code produce?

PHP

<?php
function multiply($x, $y) {
    return $x * $y;
}
echo multiply(4);
?>

A Warning: Missing argument 2 for multiply()

B Fatal error: Call to undefined function multiply()

C Output: 4

D No output, code runs fine

💡 Hint

Check how many arguments the function expects and how many are given.

The function multiply expects 2 arguments but only 1 is given, causing a warning about missing argument.

❓ Predict Output

advanced

Output of recursive function

What is the output of this PHP code?

PHP

<?php
function factorial($n) {
    if ($n <= 1) {
        return 1;
    } else {
        return $n * factorial($n - 1);
    }
}
echo factorial(4);
?>

A 24

B 10

C Error: Maximum function nesting level reached

D 4

💡 Hint

Factorial of 4 is 4*3*2*1.

The recursive function calculates factorial correctly. 4*3*2*1 = 24.

🧠 Conceptual

expert

Function variable scope behavior

What will be the output of this PHP code?

PHP

<?php
$x = 10;
function test() {
    $x = 5;
    echo $x . ' ';
}
test();
echo $x;
?>

A 10 10

B 5 10

C 5 5

D 10 5

💡 Hint

Variables inside functions have their own scope unless declared global.

Inside the function, $x is 5 (local). Outside, $x remains 10 (global). So output is '5 10'.