Summary  
This chapter covers conditional compilation using preprocessor directives (#if, #ifdef, #ifndef, #else, #elif, #endif) and the #error directive to include or exclude code and generate compile-time errors based on macro definitions.

General domain of usage  
Debug and release build configuration.

```
#define DEBUG_MODE
#ifdef DEBUG_MODE
    printf("Debugging is enabled!\n");
#endif
```


```
#ifndef RELEASE_MODE
    printf("Running in development mode.\n");
#endif
```


You will discover the secret of compilation using the console and learn how to compile programs manually. Get to know the preprocessor better and learn how to create your own macros of varying complexity. Take your programming skills to the next level with a set of preprocessor directives that will make your programs more understandable, convenient, and make compilation flexible!

Dive into the compilation process, see how to do compilation yourself using terminal commands.

Get acquainted with macros and their varieties. You will learn how to create/delete object and functional macros, and also master new tricks for working with strings .

Create conditions for different compilation scenarios using conditional preprocessor directives.

Dive into advanced preprocessor capabilities that allow you to precisely control compilation, interact with the compiler, and create flexible, manageable code using directives and built-in macros.

Practical Use Cases

What are #ifdef and #ifndef

Error macro

解答