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

Using the Null Coalescing Operator in PHP

📖 Scenario: Imagine you are building a simple PHP script that reads user input from an array. Sometimes the input might be missing, and you want to provide a default value instead of causing an error.

🎯 Goal: You will create a PHP script that uses the null coalescing operator ?? to safely access array values and provide default values when keys are missing.

📋 What You'll Learn

Create an associative array called userInput with specific keys and values

Create a variable called defaultName with a default string value

Use the null coalescing operator ?? to assign a variable name from userInput or defaultName

Print the value of name to display the result

💡 Why This Matters

🌍 Real World

Web developers often need to handle missing data safely when reading user input or configuration settings. The null coalescing operator helps avoid errors and provides default values easily.

💼 Career

Understanding how to use the null coalescing operator is important for writing clean, error-free PHP code in web development jobs.

1

Create the user input array

Create an associative array called userInput with these exact entries: 'name' => 'Alice', 'age' => 30.

PHP

 'Alice' and 'age' => 30
// Your code here

Need a hint?

Use square brackets [] to create the array and separate key-value pairs with commas.

2

Set a default name

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

PHP

 'Alice', 'age' => 30];

// Create a variable defaultName with value 'Guest'
// Your code here

Need a hint?

Use the assignment operator = to set the string value.

3

Use the null coalescing operator

Create a variable called name and assign it the value of $userInput['name'] ?? $defaultName using the null coalescing operator ??.

PHP

 'Alice', 'age' => 30];
$defaultName = 'Guest';

// Assign name using null coalescing operator to get $userInput['name'] or $defaultName
// Your code here

Need a hint?

The null coalescing operator ?? returns the left value if it exists and is not null; otherwise, it returns the right value.

4

Print the result

Write a print statement to display the value of the variable name.

PHP

 'Alice', 'age' => 30];
$defaultName = 'Guest';
$name = $userInput['name'] ?? $defaultName;

// Print the value of name
// Your code here

Need a hint?

Use print($name); to show the value on the screen.