Comments in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of PHP code with comments

What is the output of this PHP code snippet?

PHP

<?php
// This is a single-line comment
echo "Hello"; /* This is a
multi-line comment */
echo " World!";
?>

A

Hello
 World!

B Hello World!

C

Hello/* This is a
multi-line comment */ World!

D Syntax Error

💡 Hint

Remember that comments are ignored by PHP and do not affect output.

Single-line and multi-line comments are ignored by PHP. The echo statements print 'Hello' and ' World!' consecutively, resulting in 'Hello World!'.

🧠 Conceptual

intermediate

Purpose of comments in PHP

What is the main purpose of comments in PHP code?

A To explain the code to humans without affecting execution

B To make the code run faster

C To store data inside the code

D To create variables

💡 Hint

Think about what comments do when the PHP engine runs the code.

Comments are ignored by PHP when running the code. They help programmers understand the code by adding explanations or notes.

❓ Predict Output

advanced

Output with nested comment-like syntax

What will this PHP code output?

PHP

<?php
/* Start comment
// This is not a comment
echo "Hello";
End comment */
echo "World!";
?>

A Hello

B HelloWorld!

C World!

D Syntax Error

💡 Hint

Remember that everything inside /* */ is ignored, even if it looks like code.

The entire block between /* and */ is a comment, so echo "Hello"; is ignored. Only echo "World!"; runs, printing 'World!'.

📝 Syntax

advanced

Identify syntax error with comments

Which option will cause a syntax error in PHP?

A <?php /* Unclosed multi-line comment

B <?php // Comment without closing tag

C <?php echo "Hello"; // Proper comment

D

<?php # Single-line comment
 echo "Hi"; ?>

💡 Hint

Check if all multi-line comments are properly closed.

Option A has an unclosed multi-line comment which causes a syntax error. All other options have valid comments.

🚀 Application

expert

Count lines of code excluding comments

Given this PHP code, how many lines of actual code (not comments or blank lines) does it contain?

PHP

<?php
// Initialize
$a = 5;
/* Multi-line
comment here */
$b = 10;

# Another comment
$c = $a + $b;
echo $c;
?>

A 3

B 5

C 6

D 4

💡 Hint

Count only lines with actual PHP code, ignore comments and empty lines.

The code lines are: $a = 5;, $b = 10;, $c = $a + $b;, and echo $c;. Total 4 lines.