[RESOLVED] Recursive Function to form the sum of two positive integers a and b?
CodeGuru Home VC++ / MFC / C++ .NET / C# Visual Basic VB Forums Developer.com
Results 1 to 3 of 3

Thread: [RESOLVED] Recursive Function to form the sum of two positive integers a and b?

  1. #1
    Join Date
    Sep 2011
    Posts
    2

    [RESOLVED] Recursive Function to form the sum of two positive integers a and b?

    Hi all,

    I'm new to c-sharp, so I will appreciate if you guys go easy on me.

    I have to write a recursive function to form the sum of two positive integers a and b. I have to test the program by calling it from a main program that read two integers from the keyboard and uses your function to complete and print the sum, along with two numbers. I have to call my function recSum.

    INPUT:
    Please enter first number: 4
    Please enter second number: 9

    OUTPUT:

    From start of body: 4 9
    From start of body: 3 9
    From start of body: 2 9
    From start of body: 1 9
    From start of body: 0 9
    From end of body: 1 9
    From end of body: 2 9
    From end of body: 3 9
    From end of body: 4 9


    The sum of 4 and 9 is 13.

    <---------THIS IS WHAT I HAVE SO FAR-------->

    Code:
    static void Main(string[] args)
            {
                int a, b;
                int addition;
    
                Console.Write("Please Enter First Number: ");
                a = Convert.ToInt32(Console.ReadLine());
                Console.Write("Please Enter Second Number: ");
                b = Convert.ToInt32(Console.ReadLine());
    
                Console.WriteLine();
    
                addition = recSum(a, b);
                
                Console.WriteLine("\nThe sum of {0} and {1} is {2}\n",a,b,addition);
    
            }
    
            static int recSum(int x, int y)
            {
                int result = 0;
    
                if (y >= 0)
                {
    
                    for (int i = x; i >= 0 ; i--)
                    {
                        Console.WriteLine("From start of body: {0} {1}", i, y);
    
                        if (i == 0)
                        {
                            for (int j = i+1; j <= x; j++)
                            {
                                Console.WriteLine("From end of body:   {0} {1}", j, y);
                            }
                        }
    
                    }
                    result = x + y; //should be a recursive function
                    
                }return result;
            }
    The program is working fine but if you notice, it does not have a recursive function.
    So how do I create a recursive function for this calculation.

    Please guide me.


    Thanks a lot for your time.

  2. #2
    Join Date
    Sep 2011
    Posts
    2

    Re: Recursive Function to form the sum of two positive integers a and b?

    I figured it out by myself.

    Code:
    static int recSum(int x, int y)
            {
                int result = 0;
                if (y == 0)
                {
                    return (x);
                }
                else 
                {
                    result = recSum(x + 1, y - 1);  
                }
                return result;
            }
    Okay so what it basically does is that it will increase x by one until y is equal to 0.

  3. #3
    Join Date
    Jun 2001
    Location
    Melbourne/Aus (C# .Net 4.0)
    Posts
    686

    Re: [RESOLVED] Recursive Function to form the sum of two positive integers a and b?

    Nice. Sometimes (but only if it is clear and obvious) you can use an 'inline if'.

    The following code says:

    If y is 0 then return x else return the result of recSum(x+1, y-1)

    Code:
    static int recSum(int x, int y)
    {
        return (y == 0) ? x : recSum(x + 1, y - 1);
    }
    Rob
    -
    Ohhhhh.... Old McDonald was dyslexic, E O I O EEEEEEEEEE.......

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Windows Mobile Development Center


Click Here to Expand Forum to Full Width

This is a CodeGuru survey question.


Featured


HTML5 Development Center