Credit to devdocs.io

gcc 7_cpp

1. Overview 1.1. Character sets 1.2. Initial processing 1.3. Tokenization 1.4. The preprocessing language

2. Header Files 2.1. Include Syntax 2.2. Include Operation 2.3. Search Path 2.4. Once-Only Headers 2.5. Alternatives to Wrapper #ifndef 2.6. Computed Includes 2.7. Wrapper Headers 2.8. System Headers

3. Macros 3.1. Object-like Macros 3.2. Function-like Macros 3.3. Macro Arguments 3.4. Stringizing 3.5. Concatenation 3.6. Variadic Macros 3.7. Predefined Macros 3.7.1. Standard Predefined Macros 3.7.2. Common Predefined Macros 3.7.3. System-specific Predefined Macros 3.7.4. C++ Named Operators 3.8. Undefining and Redefining Macros 3.9. Directives Within Macro Arguments 3.10. Macro Pitfalls 3.10.1. Misnesting 3.10.2. Operator Precedence Problems 3.10.3. Swallowing the Semicolon 3.10.4. Duplication of Side Effects 3.10.5. Self-Referential Macros 3.10.6. Argument Prescan 3.10.7. Newlines in Arguments

4. Conditionals 4.1. Conditional Uses 4.2. Conditional Syntax 4.2.1. Ifdef 4.2.2. If 4.2.3. Defined 4.2.4. Else 4.2.5. Elif 4.3. Deleted Code

5. Diagnostics

6. Line Control

7. Pragmas

8. Other Directives

9. Preprocessor Output

10. Traditional Mode 10.1. Traditional lexical analysis 10.2. Traditional macros 10.3. Traditional miscellany 10.4. Traditional warnings

11. Implementation Details 11.1. Implementation-defined behavior 11.2. Implementation limits 11.3. Obsolete Features

12. Invocation

13. Environment Variables

gcc / 9. Preprocessor Output