What is the result created after preprocessing code?

After processing the code with the C/C++ preprocessor, the resulting source code has all preprocessor directives executed. This means:

• All macros are replaced with their definitions (text substitution).
• Parts of the code are removed or included depending on conditional compilations (#ifdef, #ifndef, etc.).
• The contents of included files (#include) are inserted.

Ultimately, the preprocessor creates a single text file with source code ready for compilation, where there are no preprocessor commands left, only clean C/C++ code.