Question

Possible Duplicate:
generating random enums

Lets say I have the following:

enum Color {        
    RED, GREEN, BLUE 
};
Color foo;

What I want to be able to do is randomly assign foo to a color. The naiive way would be:

int r = rand() % 3;
if (r == 0)
{
    foo = RED;
}
else if (r == 1)
{
    foo = GREEN;
}
else
{ 
    foo = BLUE;
}

I was wondering if there was a cleaner way of doing this. I have tried (and failed) the following:

foo = rand() % 3; //Compiler doesn't like this because foo should be a Color not an int
foo = Color[rand() % 3] //I thought this was worth a shot. Clearly didn't work.

Let me know if you guys know of any better way which does not involve 3 if statements. Thanks.

Answer 1

You can just cast an int to an enum, e.g.

Color foo = static_cast<Color>(rand() % 3);

As a matter of style, you might want to make the code a little more robust/readable, e.g.

enum Color {        
    RED,
    GREEN,
    BLUE,
    NUM_COLORS
};

Color foo = static_cast<Color>(rand() % NUM_COLORS);

That way the code still works if you add or remove colours to/from Color at some point in the future, and someone reading your code doesn’t have to scratch their head and wonder where the literal constant 3 came from.