Skip to main content
Version: 1.3.0

Comments

Comments are recognised by the preprocessor, even in pieces of the input that are not copied. (This last point is a difference between cpp and the C# preprocessor.) The rationale for doing so when copying the input is that we do not want the preprocessor to interpret a directive that is actually in a comment. This can happen when commenting out a piece of the source code that contains a preprocessing directive: we do not want that directive to be interpreted.

When the processor is in skip mode, that is, the input is not copied, comments are also recognised. This ensures that a comment containing a conditional directive, for example #endif, does not start to interact with previous directives, like #if, or raises an error when switching from copy mode to skip mode. In other words, the interpretation of comments should always be the same. For example, we want the following input to be valid:

#if true
// #endif
#endif

Comments are blocks enclosed between /* and */, and start with // for line comments.