Redcode allows single line comments to be included in the warrior's source code by using the semi-colon ; character similar to assembly language.

The parser will ignore everything after the semi-colon (exlucding it from the parsed output) until it encounters the end of the line.

At times, redcode can be quite cryptic so comments are a useful way of documentation and explaining your code. Placing a semi-colon at the beginning of a line is also a convenient way to temporarily remove a line of code while debugging etc.

mov 0, 1
; this is a comment
add 3, 4   ; this is also a comment
;jmp -1 this line of code has been commented out and will not be included in the parsed output

The above redcode will be parsed to produce the following output. Note that comments are completed removed.

mov.i $0, $1
add.ab $3, $4

It is possible to include multi-line comments in redcode by using a FOR block with a count of zero:

This is a multi-line comment
It is a good place to explain a complex strategy
or subtle nuance of the warrior's code

Because the FOR block has a count of zero, the entire thing is completely removed during parsing.