Benchmark games, Rust, big ints and Pi

[bearophile via Digitalmars-d-learn]

John Carter:

> Your paste has expired / no longer there.... but the subject 
> has come up again...
> ...
> Do you still have your implementation hanging around?

I think it was this. *Untested*:


void main(string[] args) {
     import core.stdc.stdio, std.bigint, core.stdc.stdlib;

     immutable n = (args.length == 2) ? args[1].ptr.atoi : 100;
     BigInt acc, den = 1, num = 1;

     for (uint i, k; i < n; ) {
         immutable k2 = ++k * 2U + 1U;
         acc = (acc + num * 2U) * k2;
         den *= k2;
         num *= k;
         if (num > acc)
             continue;

         immutable d = ((num * 3 + acc) / den) % 10U;
         if (d != ((num * 4 + acc) / den) % 10U)
             continue;

         putchar('0' + d);
         if (++i % 10 == 0)
             printf("\t:%u\n", i);
         acc = (acc - den * d) * 10U;
         num *= 10U;
     }
}

Bye,
bearophile