C#中string.Substring 的用法

String.SubString(int  startIndex,int length)   
  startIndex:截取字符串開始的位置     
  length:截取字符串的長度

例子：用戶 輸入兩個數，通過逗號分隔，輸入M兩個數進行乘運算，輸入D兩個數進行除法運算。

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

namespace ConsoleApplication1
{
class Program
{
 

static double Multiply(double param1, double param2)
{
return param1 * param2;
}
static double Divide(double param1, double param2)
{
return param1 / param2;
}

static void Main(string[] args)
{

Console.WriteLine("enter 2 numbers separated with a comma:");
string input = Console.ReadLine();
int commapos = input.IndexOf(',');
double param1 = Convert.ToDouble(input.Substring(0, commapos));
double param2 = Convert.ToDouble(input.Substring(commapos + 1, input.Length - commapos - 1));
Console.WriteLine("enter M to multiply or D to divide:");
input = Console.ReadLine();
double process;
if (input == "M")
{
process = Multiply(param1,param2);
}
else
{
process = Divide(param1,param2);
}
Console.WriteLine("result:{0}", process);
Console.ReadKey();
}
}
}