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Passing variable type as function parameter

开发者 https://www.devze.com 2023-03-19 07:45 出处:网络
Is it possible to pass variable type as part of a function parameter, e.g.: void foo(varType t开发者_StackOverflow中文版ype)

Is it possible to pass variable type as part of a function parameter, e.g.:

void foo(varType t开发者_StackOverflow中文版ype)
{
  // Cast to global static
  unsigned char bar;
  bar = ((type *)(&static_array))->member;
}

I remember it has something to do with GCC's typeof and using macros?


You could make an enum for all different types possible, and use a switch to make the dereferencing:

typedef enum {
    CHAR,
    INT,
    FLOAT,
    DOUBLE
} TYPE;

void foo(TYPE t, void* x){
    switch(t){
        case CHAR:
            (char*)x;
            break;
        case INT:
            (int*)x;
            break;
         ...
    }
}


You can't do that for a function, because then it needs to know the types of the arguments (and any other symbols the function uses) to generate working machine code. You could try a macro like:

#define foo(type_t) ({ \
    unsigned char bar; \
    bar = ((type_t*)(&static_array))->member; \
    ... \
    })


Eh, of course you can. Just use a macro like so:

#include <stdio.h>
#define swap(type, foo, bar) ({type tmp; tmp=foo; foo=bar; bar=tmp;})

int main() {
  int a=3, b=0;
  swap(int, a, b); // 
0

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