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Code Comments

Part of the Fundamentals section of Coddy's Dart journey — lesson 4 of 94.

Comments are notes you write inside your code. Dart completely ignores them - they exist only to help humans understand the code.

To write a single-line comment, use //. Everything after // until the end of the line is ignored:

// This is a comment
print('Hello, Dart!');

A comment can also be written at the end of a line, after the code:

print('Hello, Dart!'); // This prints Hello, Dart!

For comments that span several lines, use /* to start and */ to end:

/* This is a multi-line comment.
   Dart ignores all of it. */
print('Welcome!');

Comments can also temporarily disable a line of code without deleting it:

// print('This line will NOT run');
print('This line will run');

Challenge

Beginner

Fix the code so that only Hello, Dart! is printed.

Replace the ? with the symbols that turn a line into a comment
The line printing Goodbye! should become a comment so it does NOT run
Only change the line that starts with ?

Cheat sheet

Comments in Dart:

Notes for humans - Dart ignores them
Can disable code temporarily without deleting it

Single-line comment:

// This is a comment
print('Hello!'); // Comment after code

Multi-line comment:

/* This is a
   multi-line comment */

Disabling code:

// print('This will NOT run');
print('This will run');

Try it yourself

void main() {
  // Type your code below
  ? print('Goodbye!');
  print('Hello, Dart!');
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction to Dart

What is Dart?The main Function Printing OutputCode Comments

4Operators Part 2

Comparison Operators Logical AND Logical OR Logical NOT Type Test Operators Recap - Making Comparisons

7Working with Strings

String Concatenation String Interpolation Multi-line Strings String Properties Basic String Methods

10Collections - Maps Basics

What are Maps?Creating a Map Accessing Values by Key Key-Value Pairs Getting Map Size Getting Keys Getting Values Checking if a Key Exists

13Null Safety In Depth

Understanding Null Nullable Types Non-Nullable Types Null Assertion Operator Late Initialization Recap - Handling Null Safely

16Fundamentals Challenges

Challenge: List of calculation Challenge: Sum of numbers Challenge: Find product

3Operators Part 1

Arithmetic Operators Integer Division Modulo Operator Increment and Decrement Assignment Shortcuts Recap - Simple Calculations

6Control Flow - Decision Making

The 'if' Statement The 'else' Statement The 'else if' Statement Recap - Simple Decisions Nested 'if' Statements The 'switch' Statement

9Collections - Lists Basics

What are Lists?Creating a List Accessing by Index Getting List Length Adding Elements Removing Elements Checking if a List is Empty Iterating Over a List

12Functions Advanced

Optional Positional Parameters Named Parameters Required Named Parameters Default Parameter Values Recap - Function Parameters

15Project: Simple Calculator

Setting Up Declaring Number

Project lesson

Creating an Operation

Project lesson

Performing Calculation

Project lesson

Displaying Result

Project lesson