2 #ifdef means if defined. If the symbol following #ifdef is defined, either using #define in prior source code or using a compiler command-line argument, the text up to the enclosing #endif is …

The role of #ifdef and #ifndef Asked 15 years, 2 months ago Modified 1 year, 3 months ago Viewed 185k times

This answer, while technically correct, doesn't accurately answer the question, and implies an incorrect usage. While the two blocks will do the same thing, nesting two ifs is not the same as …

37 #ifdef checks whether a macro by that name has been defined, #if evaluates the expression and checks for a true value c

This doesn't really answer the question "How to add a 'or' condition in #ifdef?" Please avoid code only answers, especially if you try to address the question indirectly.

My problem is first of all, understanding #ifndef and #ifdef. I also want to understand the difference between #if, #ifndef , and #ifdef. I understand that #if is basically an if statement. For exa...

C ifdef, else, endif directives Asked 10 years, 10 months ago Modified 10 years, 10 months ago Viewed 30k times

In my project, the program can do one thing of two, but never both, so I decided that the best I can do for one class is to define it depending of a #define preprocessor variable. The following cod...

May 28, 2017 · Using #ifdef the above becomes much more complicated, especially getting the #else part to work. I work on code that uses conditional compilation extensively and we have a …

I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this?