Union types in PHP - Mini Project: Build & Apply

Using Union Types in PHP

📖 Scenario: You are building a simple PHP program that handles user input which can be either a number or a text message. You want to accept both types safely using PHP's union types feature.

🎯 Goal: Create a function that accepts a parameter which can be either an int or a string. The function will return a message describing the type and value received.

📋 What You'll Learn

Create a function called describeInput that accepts a parameter with a union type int|string.

Inside the function, use is_int() to check if the input is an integer.

Return a string describing the input type and value.

Call the function with both an integer and a string and print the results.

💡 Why This Matters

🌍 Real World

Union types help PHP programs accept multiple types safely, which is common when handling user input or data from different sources.

💼 Career

Understanding union types is important for writing flexible and type-safe PHP code, a skill valued in modern PHP development jobs.

1

Create the describeInput function with a union type parameter

Write a function called describeInput that accepts one parameter named $input with the union type int|string. Inside the function, just return an empty string "" for now.

PHP

<?php

// Create the describeInput function with union type parameter
function describeInput(int|string $input): string {
    // Your code here
}

Need a hint?

Use function describeInput(int|string $input): string to declare the function with a union type parameter.

2

Add type checking inside the function

Inside the describeInput function, use is_int($input) to check if $input is an integer. If it is, return the string "Input is an integer: " concatenated with the value of $input. Otherwise, return "Input is a string: " concatenated with $input.

PHP

<?php

// Create the describeInput function with union type parameter
function describeInput(int|string $input): string {
    // Your code here
}

Need a hint?

Use if (is_int($input)) { ... } else { ... } to check the type and return the correct message.

3

Call the function with an integer and a string

Call the describeInput function twice: once with the integer 42 and once with the string "hello". Store the results in variables $result1 and $result2 respectively.

PHP

<?php

// Create the describeInput function with union type parameter
function describeInput(int|string $input): string {
    if (is_int($input)) {
        return "Input is an integer: " . $input;
    } else {
        return "Input is a string: " . $input;
    }
}

// Your code here

Need a hint?

Call the function with 42 and "hello" and save the results in $result1 and $result2.

4

Print the results

Print the values of $result1 and $result2 each on a new line using echo.

PHP

<?php

// Create the describeInput function with union type parameter
function describeInput(int|string $input): string {
    if (is_int($input)) {
        return "Input is an integer: " . $input;
    } else {
        return "Input is a string: " . $input;
    }
}

$result1 = describeInput(42);
$result2 = describeInput("hello");

// Your code here

Need a hint?

Use echo $result1 . "\n"; and echo $result2 . "\n"; to print each result on its own line.