Fibonacci numbers in D

Example for versions D1, D2, gdc 0.24

This example uses iterative definition of Fibonacci numbers. 

module fibonacci;

import std.stdio;

ulong iterative(ulong x)
{
    ulong prev1 = 1L;
    ulong prev2 = 1L;
    ulong result = x <= 2 ? 1L : 0L;
    
    for ( ulong i = 3; i <= x; ++i )
    {
        result = prev1 + prev2;
        prev1 = prev2;
        prev2 = result;
    }
    return result;

}

int main()
{
	for (uint i = 1; i < 17; i++)
	{
		writef("%s, ", iterative(i));
	}
	writefln("%s", "...");
	
	return 0;
}