Comments

A comment is essentially a note in a piece of code. It’s used to add human-readable information about the code, and is completely ignored by the C# compiler.

Uses of comments

• To explain the purpose of a piece of code.
• Providing links to related resources.
• To temporarily disable a piece of code during debugging (though really, you should use a version control system for this)!
• To leave reminders or TODOs for future work.
• To document functions, classes, and other code structures - we usually use a special form of comment, called a doc comment, for this.

What we shouldn’t use comments for

• To explain what the code is doing - the code itself should be clear enough for that. If you find yourself needing to add comments to explain what the code does, consider rewriting the code to make it clearer.
• To justify bad coding practices. If you find yourself needing to add a comment to explain why you did something in a certain way, consider whether there’s a better way to do it.
• To add unnecessary information that doesn’t add value to the code.
• To rage at other developers for their bad design decisions (I know, we’ve all been there).

Single line comments

We can make a single-line comment in C# by using two forward slashes (//).
Anything after the slashes on that line is part of the comment and will be ignored by the C# compiler.

// This is a single-line comment in C#
Console.WriteLine("Hello, World!"); // This comment is after code

Multi-line comments

We can also do multi-line comments - these are comments that can span multiple lines without needing to start a new comment on each line.

We do this by starting the comment with /* and ending it with */:

/*
This is a multi-line comment in C#
It can span multiple lines
*/
Console.WriteLine( /* we can also do this */ "Hello, World!");