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C# help

Posted on 2011-03-17
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Last Modified: 2012-05-11
Hi,

I am learning C# and  I have written a small console program as follows: What  I want is the program to accept a user input that will be either string "A", "S" or "M".

and based on the user input,  a funtion will be passed to a delegate. For eg: if the user enters "A" then function "Add" should be passed to delegated and evaluated and the result should show in the console. But following program does not seem to work and I am not sure what I am doing wrong. Any help is appreciated.



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

namespace ConsoleApplication10
{
    class Program
    {

        //declare a delegate
        delegate int MethodDelegate(int num1, int num2);
     
       
       



        //Main Function
        static void Main(string[] args)
        {


            if (args.Length < 1)
            {
                Console.WriteLine("Enter an Operation Type (A/S/M):");
                args[0] = Console.ReadLine();

           
            }




            int num1 = 5;
            int num2 = 3;
            string Operation = args[0].ToString();
            MethodDelegate method = null;




            switch (Operation)
            {
                case "A": method = new MethodDelegate(Add);
                    break;
                case "S": method = new MethodDelegate(Subtract);
                    break;
                case "M": method = new MethodDelegate(Multiply);
                    break;

            }

            if (method != null)

                PerformMathOps(method, num1, num2);

            Console.ReadLine();
       
        }




        //Pass an instance of the delegate to a function
        static void PerformMathOps(MethodDelegate method, int num1, int num2)
        {
            Console.WriteLine(method(num1, num2).ToString());

        }




        //Add Function
        static int Add(int x, int y)
        {

            return (x + y);
        }


        //Subtract
        static int Subtract(int a, int b)
        {

            return (a - b);
        }


        //Multiply
        static int Multiply(int c, int d)
        {

            return (c * d);
        }




    }
}


Any help is appreciated,

thanks,
0
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Question by:Techsavy
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2 Comments
 
LVL 6

Accepted Solution

by:
nandithaa earned 2000 total points
ID: 35162492
Try this:

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

namespace ConsoleApplication10
{
    class Program
    {
        //declare a delegate
        delegate int MethodDelegate(int num1, int num2);
        string strOp = "";
        static void Main(string[] args)
        {
            args = new string[1];
            Console.WriteLine("Enter an Operation Type (A/S/M):");
            args[0] = Console.ReadLine();

            int num1 = 5;
            int num2 = 3;
            string Operation = args[0].ToString();
            MethodDelegate method = null;

            switch (Operation)
            {
                case "A": method = new MethodDelegate(Add);
                    break;
                case "S": method = new MethodDelegate(Subtract);
                    break;
                case "M": method = new MethodDelegate(Multiply);
                    break;

            }

            if (method != null)

                PerformMathOps(method, num1, num2);

            Console.ReadLine();
        }

        //Pass an instance of the delegate to a function
        static void PerformMathOps(MethodDelegate method, int num1, int num2)
        {
            Console.WriteLine(method(num1, num2).ToString());

        }

        //Add Function
        static int Add(int x, int y)
        {

            return (x + y);
        }


        //Subtract
        static int Subtract(int a, int b)
        {

            return (a - b);
        }


        //Multiply
        static int Multiply(int c, int d)
        {

            return (c * d);
        }
    }
}

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Author Closing Comment

by:Techsavy
ID: 35172343
Worked!!!
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