Null coalescing in conditions in PHP - Mini Project: Build & Apply

Null coalescing in conditions

📖 Scenario: You are building a simple PHP script to check user input from a form. Sometimes the input might be missing or empty. You want to use the null coalescing operator to provide a default value when the input is not set.

🎯 Goal: Create a PHP script that uses the null coalescing operator ?? in a condition to check if a user input variable is set. If it is not set, use a default value. Then print a message based on the value.

📋 What You'll Learn

Create a variable $input with a specific value

Create a variable $default with a default string

Use the null coalescing operator ?? in an if condition to check $input or use $default

Print the message showing which value was used

💡 Why This Matters

🌍 Real World

Web forms often have optional fields. Using null coalescing helps handle missing inputs gracefully.

💼 Career

PHP developers use null coalescing to write cleaner, safer code when dealing with user input or data that might be missing.

1

Create the user input variable

Create a variable called $input and set it to null.

PHP

<?php

// Create a variable called $input and set it to null
// Your code here

Need a hint?

Use $input = null; to create the variable.

2

Create the default value variable

Create a variable called $default and set it to the string 'Guest'.

PHP

<?php

$input = null;
// Create a variable called $default and set it to 'Guest'
// Your code here

Need a hint?

Use $default = 'Guest'; to create the variable.

3

Use null coalescing in an if condition

Write an if statement that uses the null coalescing operator ?? to check if $input is set; if not, use $default. Inside the if, check if the result equals 'Guest'.

PHP

<?php

$input = null;
$default = 'Guest';

// Use if with null coalescing operator to check $input or $default
// Check if the result equals 'Guest'
// Your code here

Need a hint?

Use if (($input ?? $default) === 'Guest') to check the value.

4

Print the result message

Inside the if block, print "Hello, Guest!". Otherwise, print "Hello, " followed by the value of $input.

PHP

<?php

$input = null;
$default = 'Guest';

if (($input ?? $default) === 'Guest') {
    // Print Hello, Guest!
} else {
    // Print Hello, $input
}

Need a hint?

Use print("Hello, Guest!"); inside the if and print("Hello, $input"); inside the else.