Composer installation and setup in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Composer command?

You run the command composer --version in your terminal after installing Composer. What output do you expect?

PHP

composer --version

A Composer version 2.5.8 2024-05-01 12:00:00

B Error: command not found

C composer.json file missing

D PHP Fatal error: Uncaught Error: Class 'Composer' not found

💡 Hint

Composer installation adds the composer command globally if installed correctly.

The composer --version command outputs the installed Composer version if Composer is installed and accessible in your system PATH.

🧠 Conceptual

intermediate

Which file does Composer use to manage dependencies?

After installing Composer, which file should you create or edit to specify your PHP project dependencies?

A composer.lock

B vendor.php

C autoload.php

D composer.json

💡 Hint

This file is a JSON file that lists your project requirements.

Composer uses composer.json to define project dependencies and settings. The composer.lock file is generated automatically to lock versions.

🔧 Debug

advanced

Why does this Composer install command fail?

You run composer install but get the error: Could not open input file: composer.phar. What is the most likely cause?

PHP

composer install

A composer.json file is empty

B PHP version is too old to run Composer

C Composer is not installed globally or composer.phar is missing in the current directory

D Network connection is down

💡 Hint

Composer can be installed globally or as a local .phar file.

The error means the system tried to run php composer.phar but the file composer.phar was not found. This happens if Composer is not installed globally and you are not in the directory with composer.phar.

📝 Syntax

advanced

Which command correctly installs Composer globally on Linux?

Choose the correct sequence of commands to install Composer globally on a Linux system.

A php composer.phar install && sudo mv composer.phar /usr/local/bin/composer

B php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" && php composer-setup.php && sudo mv composer.phar /usr/local/bin/composer

C wget https://getcomposer.org/composer.phar && chmod +x composer.phar && sudo mv composer.phar /usr/local/bin/composer

D curl -sS https://getcomposer.org/installer | php && sudo mv composer.phar /usr/local/bin/composer

💡 Hint

The official recommended method downloads the installer script first.

Option B downloads the installer script, runs it to create composer.phar, then moves it to a global location. Option B moves composer.phar with sudo and to /usr/local/bin which is correct. Option B downloads composer.phar directly but misses installer verification. Option B assumes composer.phar exists and runs install incorrectly.

🚀 Application

expert

After installing Composer, how do you autoload classes in your PHP project?

You have installed dependencies with Composer. Which PHP code snippet correctly includes the Composer autoloader to use installed packages?

A require 'vendor/autoload.php';

B include 'composer.json';

C require 'autoload.php';

D include 'vendor/composer.php';

💡 Hint

Composer generates an autoload file inside the vendor directory.

Composer creates vendor/autoload.php which you include in your PHP scripts to load all dependencies automatically.