Array of Union on C

Question

I have declared this array of unions:

union Function {
    char* name;
    double (*fnct)();
    int args;
};

union Function functions[] = {
    {.name = "acos", .fnct = acos, .args = 1},
    {.name = "asin", .fnct = asin, .args = 1},
    {.name = "atan", .fnct = atan, .args = 1},
};

But, when I try to use it I get an Segmentation fault error.

for(int i = 0; i < sizeof(functions) / sizeof(union Function); i++) {
    printf("%d\n", functions[i].args);
    printf("%s\n", functions[i].name); //HERE!
}

Answer 1

A union contains either of its members, not all of its members.

So the last initializer is the final one, meaning its value is just 1. So printing the name ( a string) results in a seg fault because printf tries to dereference the address 1.

If you want to have all of its members, use struct instead of union.