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

Null safe operator

📖 Scenario: Imagine you have a list of people, and each person may or may not have a car. You want to check the color of each person's car safely without causing errors if the car is missing.

🎯 Goal: Build a PHP script that uses the null safe operator to safely access the car color of each person.

📋 What You'll Learn

Create a class Car with a public property color.

Create a class Person with a public property car that can be null or a Car object.

Create an array people with some Person objects, some with cars and some without.

Use the null safe operator ?-> to get the car color safely for each person.

Print the car color or "No car" if the person has no car.

💡 Why This Matters

🌍 Real World

In real applications, objects may or may not have related objects. The null safe operator helps avoid errors when accessing properties of objects that might be missing.

💼 Career

Understanding the null safe operator is important for writing clean and error-free PHP code, especially when working with APIs, databases, or complex data structures.

1

Create classes and people array

Create a class called Car with a public property color. Create a class called Person with a public property car. Then create an array called people with three Person objects: the first has a Car with color "red", the second has no car (null), and the third has a Car with color "blue".

PHP

<?php
// Create classes Car and Person
// Create array people with 3 Person objects

Need a hint?

Define the classes with public properties and create the array with the exact objects and values.

2

Add a variable for the people array

Create a variable called people that holds the array of Person objects you created in Step 1.

PHP

<?php
// people array already created
// Your code here

Need a hint?

The $people variable should already be set from Step 1.

3

Use null safe operator to get car colors

Use a foreach loop with variable $person to iterate over $people. Inside the loop, create a variable $color that uses the null safe operator ?-> to get the color property of the car property of $person. If the car is missing, $color should be null.

PHP

<?php
foreach ($people as $person) {
    // Use null safe operator to get car color
    // Your code here
}

Need a hint?

Use ?-> to safely access color from car.

4

Print car colors or 'No car'

Inside the foreach loop, print the value of $color if it is not null. Otherwise, print "No car". Use echo to display the output followed by a newline.

PHP

car?->color;
    // Print $color or "No car"
    // Your code here
}

Need a hint?

Use the null coalescing operator ?? to print $color or "No car".