how in #ifdef identifier and #ifndef identifier declare identifiers...

ifndef with multiple AND conditions in makefile gnu...

Using ifndef in the makefile inside a variable defined by export...

about #ifndef and macro_function...

#ifndef not letting my files see what's in the header (C++)...

Compilation error while including header file in compile command...

Can/should I type whatever I want after #ifndef?...

Include Guards in C...

Multiple definition of namespace::variable even using ifndef...

Multiple definition of namespace function...

Multiple #ifndef statements - which one gets applied...

possible to use #ifndef on a function name?...

Confusion with Preprocessor Directives...

How to combine ifndef win32 with ifndef iOS...

How to execute a part of code inside a function only once using #ifndef?...

Unexpected #ifndef, No Matching Function Call (Linked List C++)...

C header file #ifndef #include error...

Conditional exclusion of code in Swift...

How does the preprocessor know to translate HEADER_H to header.h?...

Do I check the existence of a macro function with or without the parens?...

C++ #ifndef TOKEN #define TOKEN...

WHY "already defined"?...

ifndef, define & direct assignment of constants...

How #ifndef works in different files...

Can #ifndef ignore method or variable duplications?...

Why only define a macro if it's not already defined?...

Having trouble with #ifndef in C++...

#ifndef why to use an other name than the class name?...

error while programming c++ using header...

User Defined Build Settings in Test Targets?...