可变长函数指针

var_arg_func_ptr_demo.cpp

#include <stdio.h>
#include <stdarg.h>

typedef void (*f_type)(int, ...);
void foo1(int n1) { printf("%d\n", n1); }
void foo2(int n1, int n2) { printf("%d %d\n", n1, n2); }
void foo3(int n1, int n2, int n3) { printf("%d %d %d\n", n1, n2, n3); }

void bar(f_type pf, ...) {
    if ((void *)pf == (void *)foo1) {
        va_list args;
        va_start(args, pf);
        int n1 = va_arg(args, int);
        va_end(args);
        foo1(n1);
    } else if ((void *)pf == (void *)foo2) {
        va_list args;
        va_start(args, pf);
        int n1 = va_arg(args, int);
        int n2 = va_arg(args, int);
        va_end(args);
        foo2(n1, n2);
    } if ((void *)pf == (void *)foo3) {
        va_list args;
        va_start(args, pf);
        int n1 = va_arg(args, int);
        int n2 = va_arg(args, int);
        int n3 = va_arg(args, int);
        va_end(args);
        foo3(n1, n2, n3);
    }
}

int main(int, char**) {
    int a=3, b=4, c=5;
    bar((f_type)foo1, a);
    bar((f_type)foo2, a, b);
    bar((f_type)foo3, a, b, c);
    return 0;
}