Array reduce function in PHP - Mini Project: Build & Apply

Array reduce function

📖 Scenario: You are working on a simple shopping cart system. You have a list of prices for items a customer wants to buy.

🎯 Goal: You will use PHP's array_reduce function to calculate the total price of all items in the cart.

📋 What You'll Learn

Create an array called prices with the exact values: 10, 20, 30, 40

Create a variable called initial and set it to 0

Use array_reduce with a callback function named sum that adds two numbers

Store the result of array_reduce in a variable called total

Print the value of total

💡 Why This Matters

🌍 Real World

Calculating totals from lists of numbers is common in shopping carts, billing systems, and data analysis.

💼 Career

Understanding how to use array functions like <code>array_reduce</code> helps you write cleaner and more efficient PHP code in real projects.

1

Create the prices array

Create an array called prices with the exact values 10, 20, 30, and 40.

PHP

<?php

// Create the prices array with 10, 20, 30, 40
// Your code here

Need a hint?

Use square brackets [] to create the array and separate values with commas.

2

Set the initial value

Create a variable called initial and set it to 0.

PHP

<?php

$prices = [10, 20, 30, 40];

// Create the initial value variable and set it to 0
// Your code here

Need a hint?

Just assign 0 to a variable named initial.

3

Use array_reduce to sum prices

Use array_reduce with a callback function named sum that takes two parameters and returns their sum. Store the result in a variable called total. Use $prices as the array and $initial as the initial value.

PHP

<?php

$prices = [10, 20, 30, 40];

$initial = 0;

// Use array_reduce with a callback function sum to add values
// Store the result in total
// Your code here

Need a hint?

Define a function sum that adds two numbers. Then call array_reduce with $prices, the function name as a string, and $initial.

4

Print the total price

Print the value of the variable total.

PHP

<?php

$prices = [10, 20, 30, 40];

$initial = 0;

function sum($carry, $item) {
    return $carry + $item;
}

$total = array_reduce($prices, 'sum', $initial);

// Print the total
// Your code here

Need a hint?

Use print($total); to show the total price.