ILE C/C++ Compiler Reference


Preprocessor Overview

Preprocessing is a preliminary operation on C and C++ files before they are passed to the compiler. Preprocessing lets you:

A token is a series of characters delimited by white space. The only white space allowed on a preprocessor directive is the space, horizontal tab, vertical tab, form feed, and comments. The new-line character can also separate preprocessor tokens.

The preprocessed source program file must be a valid C or C++ program.

The preprocessor is controlled by the following directives:

#define
Defines a preprocessor macro.

#undef
Removes a preprocessor macro definition.

#error
Defines text for a compile-time error message.

#include
Inserts text from another source file.

#if
Conditionally suppresses portions of source code, depending on the result of a constant expression.

#ifdef
Conditionally includes source text if a macro name is defined.

#ifndef
Conditionally includes source text if a macro name is not defined.

#else
Conditionally includes source text if the previous #if, #ifdef, #ifndef, or #elif test fails.

#elif
Conditionally includes source text if the previous #if, #ifdef, #ifndef, or #elif test fails, depending on the value of a constant expression.

#endif
Ends conditional text.

#line
Supplies a line number for compiler messages.

#pragma
Specifies implementation-defined instructions to the compiler.


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