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Questions tagged [variadic-macros]

Variadic macros are a feature of the C-preprocessor that permit a variable number of arguments to a macro. They were added in the 1999 revision of the C standard.

Variadic macros are a feature of the C-preprocessor that permit a variable number of arguments to a macro. They were added in the 1999 revision of the C standard.

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295 questions
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C99 compatible nested calls within variadic macros

Need a way to support nested calls in variadic macros with optional argument. same as this but C99 compatible GNU gcc extension for ## operator prevents nested calls from being expanded, see code below. #define send(obj, msg, ...) find_method(obj,…
Viktor Shepel
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C++ variadic templates function in variadic macro

I'm currently working on a project where I need to simplfy an existing system. Wihtout going into the details the problem is that I get some function pointer (from type: void*) and I need to create a function from it (= create a function with…
MainCPP
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C Preprocessor, Macro "Overloading"

I'm trying to do some kind of Macro "Overloading", so that MACRO(something), gets expanded differently than MACRO(something, else). Using a snippet I got from here (I'm not sure if it's 100% portable) and some functions from the Boost PP Library, I…
Ale Morales
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How could I replace variadic template expansion with macro in c++

I've got the following code: template constexpr static const inline int sc(Args&&... args) { return scanf(_hidden::fmt< decltype(args+0)... >::result::data, …
Denis Sheremet
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How to expand macro and delete comma

For example I want to write my own printf() alternative, but I have to perform calculations on the variable arguments: #define log(fmt_string, ...) my_log(fmt_string, pack_args(__VA_ARGS__), __VA_ARGS__) where pack_args(...) - is a macro too. How…
Anton Kochkov
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Variadic macros: expansion of pasted tokens

I'm wondering if it's possible to "nest" variadic macro invocations. I'm only truly concerned with GCC and Clang. My macro definition looks like this: /** * @brief Invoke an instance method. */ #define $(obj, method, ...) \ ({ \ …
jdolan
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A group of variadic macros

I would like to have a group of variable number of arguments passed into a macro. I have following macros which is incorrect: #define M_NARGS(...) M_NARGS_(__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) #define M_NARGS_(_10, _9, _8, _7, _6, _5, _4,…
yuefengz
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Writing a variadic macro that uses the names of the arguments passed

I want to write a variadic macro that somehow knows the names of the arguments passed. For example: The code: int x = 2; float f = 4.6; char c = 'A'; char* str = "Bla bla"; PRINT("%d %f %c %s", x, f, c, str); // calling the macro shall…
user3115040
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Creating list of stringized macro arguments with variadics and late expansions

I have the following problem - given variable number of macro arguments argX to create a list of stringized arguments #argX Example: LIST(A, B) -> "A", "B" LIST(A, B, C) -> "A", "B", "C" I'm using Boost, so the above macro is not too difficult to…
user2971693
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Variadac Macro apply macro to all arguments

I was experimenting with C++11 variadac macros. I was trying to apply another macro to each argument in the list. This is my first try: #define APPLY_CHAIN(first, ...) APPLY_ACT(first) APPLY_CHAIN( __VA_ARGS__ ) Unfortunately this did not work.…
Martin York
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Avoiding "ISO C99 requires rest arguments to be used"

With gcc 4.6.3 (with -ansi -pedantic), I've got the following code: // Argument counting macro #define NARGS(...) NARGS_(__VA_ARGS__, 5, 4, 3, 2, 1) #define NARGS_(_1, _2, _3, _4, _5, _, ...) _ static inline void fi_init_(size_t nargs, fileinfo_t…
gct
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How to pass arguments to a variadic macro?

I have a variadic function: LogWrite(FILE * fp, int level, const char * filename, const char * function, ...) It should be called like this: LogWrite(fp, int Level, __FILE__, __FUNCTION__, "Message: %s", message) However, I want to write a…
Sagar
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Macroized Parameters

I have a system with many parameter sets "macroized" (macros of the form "#define name value,value,value). I would like to pass these to a macro, but when I do I get an error. example: void fn(int a, int b, int c){ return; } #define MACRO_1(a, b,…
tletnes
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Variadic macros with zero arguments doesn't compile even with ##__VA_ARGS__

If I try to compile the following code: template void Dummy(const TArgs &...args) { } #define DUMMY(...) Dummy("Hello", ##__VA_ARGS__) int main() { DUMMY(); } I get the following compilation error: g++ -std=c++17 -O3 -Wall…
anton_rh
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Variadic macros

Is there any way to write a macro like this: #define G(x1, x2, ... , xn) f(x1), f(x2), ... , f(xn) Or do I need to define this for each individual n? C++0x answers are ok. Edit: I'm asking how to create a macro of this form, not a macro that takes…
Clinton
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