Preprocessor Directives In C Programming

C Preprocessor Directives Tutorial The Eecs Blog 6 because ## is a token concatenation operator for the c preprocessor. or maybe i don't understand the question. C# preprocessor differentiate between operating systems asked 10 years, 2 months ago modified 8 months ago viewed 18k times.

Preprocessor Directives In C Programming Btech Geeks Fyi, identifiers names, including preprocessor symbols, beginning with an underscore followed by a capital letter (or beginning with two underscores) are reserved to the implementation by the c and c standards; they shouldn't really be used in "ordinary" code. 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. 4 if your compiler sets a preprocessor macro like debug or ndebug you can make something like this (otherwise you could set this up in a makefile): #ifdef debug #define my compiler assert(expression) switch (0) {case 0: case (expression):;} #else #define my compiler assert(expression) #endif then, your compiler asserts only for debug builds. A preprocessor is an "engine" executed before the compiler compiles code. #define #include are preprocessor directives or macros, so the preprocessor engine executes code related to the directives.

C Preprocessor Directives C Programming C Tutorial Wikitechy 4 if your compiler sets a preprocessor macro like debug or ndebug you can make something like this (otherwise you could set this up in a makefile): #ifdef debug #define my compiler assert(expression) switch (0) {case 0: case (expression):;} #else #define my compiler assert(expression) #endif then, your compiler asserts only for debug builds. A preprocessor is an "engine" executed before the compiler compiles code. #define #include are preprocessor directives or macros, so the preprocessor engine executes code related to the directives. I want to do something like: #ifdef gcc #define getfunctionname() string("my function name is ") pretty function ; #endif since i want to use pretty function , this is only supported by gnu as far as i know so i need to detect if i am compiling for g and mingw, how can i do that? i'm guessing all i need to know are the compiler's preprocessor definitions, like i did for microsoft. Doing it as a parametrised macro is a bit odd. just do something like this: #ifdef use const #define myconst const #else #define myconst #endif then you can write code like this: myconst int x = 1; myconst char* foo = "bar"; and if you compile with use const defined (e.g., typically something duse const in the makefile or compiler options) then it will use the consts; otherwise it won't. So, if the tested macro and the value macros are defined as lists of character values, then they can be compared directly in a preprocessor #if conditional and in order to print such macros in a pragma message, use of stringifying macros are required. C preprocessor directives macros are just another form of "meta programming", albeit a relatively cruder form than is available in other languages. preprocessor directives instruct the compiler to do certain things at compile time, such as to ignore certain code on certain platforms, or to find and replace a string in the code with another string.

C Programming Preprocessor Directives Trytoprogram I want to do something like: #ifdef gcc #define getfunctionname() string("my function name is ") pretty function ; #endif since i want to use pretty function , this is only supported by gnu as far as i know so i need to detect if i am compiling for g and mingw, how can i do that? i'm guessing all i need to know are the compiler's preprocessor definitions, like i did for microsoft. Doing it as a parametrised macro is a bit odd. just do something like this: #ifdef use const #define myconst const #else #define myconst #endif then you can write code like this: myconst int x = 1; myconst char* foo = "bar"; and if you compile with use const defined (e.g., typically something duse const in the makefile or compiler options) then it will use the consts; otherwise it won't. So, if the tested macro and the value macros are defined as lists of character values, then they can be compared directly in a preprocessor #if conditional and in order to print such macros in a pragma message, use of stringifying macros are required. C preprocessor directives macros are just another form of "meta programming", albeit a relatively cruder form than is available in other languages. preprocessor directives instruct the compiler to do certain things at compile time, such as to ignore certain code on certain platforms, or to find and replace a string in the code with another string.