What are the best practices for using C++ preprocessor directives?

What are the best practices for using C++ preprocessor directives?

When using C++ preprocessor directives, it's best to limit their use to avoid code complexity. Use include guards to prevent multiple inclusions, and prefer #define for constants over macros.

Can you explain what include guards are?

Include guards are preprocessor directives that prevent a header file from being included multiple times. They typically look like this:

#ifndef HEADER_FILE_NAME_H
#define HEADER_FILE_NAME_H

// Your code here

#endif // HEADER_FILE_NAME_H

What about using #define versus const?

Using const is generally preferred over #define for constants because const has type safety and scope, while #define is just a text replacement.

Are there any performance implications of using preprocessor directives?

Yes, excessive use of preprocessor directives can lead to longer compilation times and larger binary sizes. It's important to use them judiciously.