| Basic concepts | ||||
| Keywords | ||||
| Preprocessor | ||||
| Statements | ||||
| Expressions | ||||
| Initialization | ||||
| Declarations | ||||
| Functions | ||||
| Miscellaneous | ||||
| History of C | ||||
| Technical Specifications |
The preprocessor is executed attranslation phase 4, before the compilation. The result of preprocessing is a single file which is then passed to the actual compiler.
Contents |
The preprocessing directives control the behavior of the preprocessor. Each directive occupies one line and has the following format:
# characterdefine,undef,include,if,ifdef,ifndef,else,elif,elifdef,elifndef(since C23),endif,line,embed(since C23),error,warning(since C23),pragma)[1]The null directive (# followed by a line break) is allowed and has no effect.
The preprocessor has the source file translation capabilities:
#if,#ifdef,#ifndef,#else,#elif,#elifdef,#elifndef(since C23) and#endif).#define and#undef, and operators# and##)#includeand checked with__has_include(since C23))#error or#warning respectively(since C23))The following aspects of the preprocessor can be controlled:
#pragma and operator_Pragma(since C99))#line)| This section is incomplete Reason: no example |
C documentation forPredefined Macro Symbols | |
C documentation forMacro Symbol Index | |
C++ documentation forPreprocessor |
