Question

尝试确定我的整数列表是由奇数还是偶数组成，我想要的输出是真和/或假的列表。我可以在列表lst上执行以下操作，还是需要创建循环？ A是输出。

    List <int> lst = new List <int>();
    A = IsOdd(lst);

Answer 1

只需使用模数

遍历列表并在每个项目上运行以下内容

if(num % 2 == 0)
{
  //is even
}
else
{
  //is odd
}

或者，如果你想知道是否所有都是偶数，你可以做这样的事情：

bool allAreEven = lst.All(x => x % 2 == 0);

Answer 2

您可以尝试使用Linq投影列表：

var output = lst.Select(x => x % 2 == 0).ToList();

这将返回一个新的bool列表，{1, 2, 3, 4, 5}将映射到{false, true, false, true, false}。

Answer 3

至少有7种不同的方法来测试数字是奇数还是偶数。但是，如果你read through these benchmarks，你会发现上面提到的TGH，模数运算是最快的：

if (x % 2 == 0)
               //even number
        else
               //odd number

以下是一些其他方法（来自website）：

//bitwise operation
if ((x & 1) == 0)
       //even number
else
      //odd number

//bit shifting
if (((x >> 1) << 1) == x)
       //even number
else
       //odd number

//using native library
System.Math.DivRem((long)x, (long)2, out outvalue);
if ( outvalue == 0)
       //even number
else
       //odd number

Answer 4

        #region even and odd numbers
        for (int x = 0; x <= 50; x = x + 2)
        {

            int y = 1;
            y = y + x;
            if (y < 50)
            {
                Console.WriteLine("Odd number is #{" + x + "} : even number is #{" + y + "} order by Asc");
                Console.ReadKey();
            }
            else
            {
                Console.WriteLine("Odd number is #{" + x + "} : even number is #{0} order by Asc");
                Console.ReadKey();
            }

        }

        //order by desc

        for (int z = 50; z >= 0; z = z - 2)
        {
            int w = z;
            w = w - 1;
            if (w > 0)
            {
                Console.WriteLine("odd number is {" + z + "} : even number is {" + w + "} order by desc");
                Console.ReadKey();
            }
            else
            {
                Console.WriteLine("odd number is {" + z + "} : even number is {0} order by desc");
                Console.ReadKey();
            }
        }

Answer 5

- 简单代码 -

#endregion #region奇数/偶数按desc排序

        //declaration of integer
        int TotalCount = 50;
        int loop;


        Console.WriteLine("\n---------Odd Numbers -------\n");


        for (loop = TotalCount; loop >= 0; loop--)
        {


            if (loop % 2 == 0)
            {
                Console.WriteLine("Even numbers : #{0}", loop);
            }



        }

        Console.WriteLine("\n---------Even Numbers -------\n");

        for (loop = TotalCount; loop >= 0; loop--)
        {


            if (loop % 2 != 0)
            {
                Console.WriteLine("odd numbers : #{0}", loop);
            }


        }

到Console.ReadLine（）;

        #endregion

测试整数列表是奇数还是偶数

5 个答案: