using System;

using System.Collections.Generic;

public class Program

{

        public static void Main()

        {

            var genders = new List<bool> { false, true, true };

            var counts = CountBoysAndGirls(genders);

​

            Console.WriteLine(counts.boys); // 輸出 "2"

        }

​

        // 計算串列中的男生和女生數量，並以 tuple 傳回。

        static (int boys, int girls) CountBoysAndGirls(List<bool> genders)

        {

            var result = (boys: 0, girls: 0);

            foreach (var gender in genders)

            {

                ref int count = ref (gender ? ref result.boys : ref result.girls);

                count++;

            }

            return result;

        }

​

}