/*

* Union initializers are part of C99 but not C++.

*

* Embed the test union inside a struct because there was an issue with

* that in VS2013 and union-inside-struct is needed by API macros.

*/

#include <stdio.h>

typedef union {

int a;

double b;

const char *c;

} test_union;

typedef struct {

int etype; /* 0=int, 1=double, 2=string */

test_union u;

} test_struct;

static void dump_struct(test_struct *t) {

switch (t->etype) {

case 0:

printf("Integer: %d\n", t->u.a);

break;

case 1:

printf("Double: %lf\n", t->u.b);

break;

case 2:

printf("String: %s\n", t->u.c);

break;

default:

printf("Unknown type: %d\n", t->etype);

}

}

int main(int argc, char *argv[]) {

test_struct v1 = { 0, 123 }; /* default is to initialize first alternative */

test_struct v2 = { 0, { .a = 234 } };

test_struct v3 = { 1, { .b = 123.456 } };

test_struct v4 = { 2, { .c = "foo" } };

dump_struct(&v1);

dump_struct(&v2);

dump_struct(&v3);

dump_struct(&v4);

}