Selecting functions using C preprocessor symbol concatenation.

preprocessor_monstrosities_1.c

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

void f1() {
    printf("a\n");
}

void f2() {
    printf("b\n");
}

void f3(const char * fmt, ...) {
    va_list vaList;

    va_start(vaList, fmt);

    vfprintf(stderr, fmt, vaList);

    va_end(vaList);
}

#define PICK(n, ...) f##n (__VA_ARGS__)


int main() {

    PICK(1);
    PICK(2);
    PICK(1);
    PICK(3,"Massive %s\n", "d*!@ery");

    return 0;
}