test.cpp

#include <stdio.h>

typedef union mytype {
	const char *string;
	int num;

    mytype(int n) : num(n) {}
	mytype(const char *n) : string(n) {}
} mytype;

template<int pass>
mytype test() {
	if(pass == 1) {
		mytype a = {"string"};
		return a;
	} else {
		mytype b = {1};
		return b;
    }
}

int main(int argc, char **argv) {
	printf("%s\n", test<1>().string);
	printf("%i\n", test<0>().num);
	return 0;
}