sieve.zen

//
// The Zen Programming Language(tm)
// Copyright (c) 2018-2020 kristopher tate & connectFree Corporation.
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
//
// This project may be licensed under the terms of the ConnectFree Reference
// Source License (CF-RSL). Corporate and Academic licensing terms are also
// available. Please contact <licensing@connectfree.co.jp> for details.
//
// Zen, the Zen three-circles logo and The Zen Programming Language are
// trademarks of connectFree Corporation in Japan and other countries.
//
// connectFree and the connectFree logo are registered trademarks
// of connectFree Corporation in Japan and other countries. connectFree
// trademarks and branding may not be used without express written permission
// of connectFree. Please remove all trademarks and branding before use.
//
// See the LICENSE file at the root of this project for complete information.
//
//

//
// sieve.zen
// Sieve of Eratosthenes
// 20200610, tkoki
//

const std = @import("std");
const heap = std.heap;

fn isPrimeNumber(n: u32) bool {
    var i: u32 = 2;
    var is_prime: bool = false;

    if (n == 1) {
        return false;
    } else if (n == 2) {
        return true;
    }
    while (true) {
        if (n % i == 0) {
            is_prime = false;
            break;
        } else {
            i += 1;
            if (i == n) {
                is_prime = true;
                break;
            }
        }
    }
    return is_prime;
}

pub fn main() anyerror!void {
    var arena = heap.ArenaAllocator{ .allocator = heap.page_allocator };
    defer arena.deinit();

    const args = try std.process.argsAlloc(&mut arena);

    if (args.len > 1) {
        const max_number = try std.fmt.parseInt(u32, args[1], 10);
        std.debug.printInfo("max_number = {}", .{max_number});
        var i: u32 = 1;
        while (i <= max_number) {
            if (isPrimeNumber(i)) {
                std.debug.printInfo("{} is prime number.", .{i});
            }
            i += 1;
        }
    }
}