preprocessor-directive

I have a pretty big codebase and I wanted to clean it out by removing and applying some ifdef's scattered around it. For example, I have lot's of these: test.c #ifdef MYCHECK // do other sutff #else // do stuff #endif Is there a tool that allows me to run through the entire codebase and remove all that code, leaving only the code inside my variable condition? For example: nicetool -D MYCHECK *.c Would result in: test.c // do other stuff It looks like unifdef is what you want, it is also used in the Linux kernel . This is the description of the tool from the linked site ( emphasis mine ): The

I have never worked with #if , #ifdef , #ifndef , #else , #elif and #endif . As I was going through some source-codes, I found an extensive use of these directives. Did some reading on conditional-preprocessors but found no clue like how are they different from normal conditional statements . So I was wondering what is the advantage of following code: #include<iostream> int main() { int i = 0; #if i == 0 std::cout<<"This"; #else std::cout<<"That"; #endif return 0; } over this: #include<iostream> int main() { int i = 0; if (i == 0) std::cout<<"This"; else std::cout<<"That"; return 0; } Also,

I've used a code base before that had a macro system for enabling and disabling sections of code. It looked something like the following: #define IN_USE X #define NOT_IN_USE _ #if defined( WIN32 ) #define FEATURE_A IN_USE #define FEATURE_B IN_USE #define FEATURE_C NOT_IN_USE #elif defined( OSX ) #define FEATURE_A NOT_IN_USE #define FEATURE_B NOT_IN_USE #define FEATURE_C IN_USE #else #define FEATURE_A NOT_IN_USE #define FEATURE_B NOT_IN_USE #define FEATURE_C NOT_IN_USE #endif Then the code for the features would look like: void DoFeatures() { #if USING( FEATURE_A ) // Feature A code... #endif

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 example: #include<iostream> #define LINUX_GRAPHICS 011x101 int main(){ long Compare = LINUX_GRAPHICS; #if Compare == LINUX_GRAPHICS std::cout << "True" << std::endl; #endif } But the others, although I read about them I can't comprehend. They also seem like very similar terms, but I doubt they work similarly. Help would be greatly appreciated. Macros are expanded by the preprocessor who doesnt know

I know that I can use preprocessor directives to check for Debug/Release by doing this: #if DEBUG //debug mode #elif //release mode #endif but what about checking for other configurations, like Test. In VB you can do this: #If CONFIG = "Release" Then 'Release mode #ElseIf CONFIG = "Test" Then 'Test mode #ElseIf CONFIG = "Debug" Then 'Debug mode #End If So, my question is in C#, how can I check for Test mode? I have some code that I want to execute if I'm in Debug AND Test, but not in Release mode, so specifically, I need a way to check for not being in Release mode. In VB I would do this: #If

I am a first year computer science student and my professor said #define is banned in the industry standards along with #if , #ifdef , #else , and a few other preprocessor directives. He used the word "banned" because of unexpected behaviour. Is this accurate? If so why? Are there, in fact, any standards which prohibit the use of these directives? Jonathan Leffler First I've heard of it. No; #define and so on are widely used. Sometimes too widely used, but definitely used. There are places where the C standard mandates the use of macros — you can't avoid those easily. For example, §7.5 Errors