C#中四舍5入的方法

一点小总结,与大家分享:

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            //Floor向负无穷方向舍入为最接近的整数
            Console.WriteLine(decimal .Floor(-1.3m)); //-2
            Console.WriteLine(decimal .Floor (3.5m)); //3
            Console.WriteLine(decimal .Floor (4m));   //4

            //Truncate向零方向舍入为整数
            Console.WriteLine(decimal.Truncate(-1.3m));//-1
            Console.WriteLine(decimal.Truncate (3.5m));//3
            Console.WriteLine(decimal.Truncate (4m));  //4
           
            //如果想实现四舍五入，则必须用下面的技巧，保留到小数点后2位，就用100，保留到小数点后3位就用1000，依次类推
            decimal a = 8.335m,b=8.345m;
            Console.WriteLine(decimal .Truncate (a*100+0.5m)/100); //8.34
            Console.WriteLine (decimal .Truncate (b*100+0.5m)/100); //8.35

            //总结，System.Double(double)和System.Single(float)结构都没有这2种方法，所以一般用decimal来实现取整
        }
    }
}