C/C++ Programmer's Guide (G06.25+)

Preprocessor Directives and Macros

HP C/C++ Programmer’s Guide for NonStop Servers—429301-002

12-10

#line

The #line directive causes the compiler to renumber the lines of the source text so

that the next line has the specified number and causes the compiler to believe that the

current source file name is file-name. If file-name is not specified, then only the

renumbering of lines takes place.

#pragma

The #pragma directive instructs the preprocessor to pass a compiler pragma on to the

compiler.

compiler-pragma

is any compiler pragma described in Section 13, Compiler Pragmas.

newline

is the newline character that terminates the directive line.

Example

This example enables run-time error checking:

#pragma CHECK

#undef

The #undef directive deletes a macro definition created using #define.

identifier

is the name of the macro to delete.

Usage Guideline

Once you have deleted a macro definition, its identifier no longer exists as a macro

name. Consequently, the #ifdef and #ifndef directives will find the identifier to be

undefined.

#line number [file-name]

#pragma compiler-pragma [ , compiler-pragma ]... newline

#undef identifier