How to use if..else for positive integers only

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I want to use the if..else statement to only accept positive integers without needing catch(formatException)

What I have tried:

//ExceptionHandling.cs
//write a program not catching every exception
using System;

class ExceptionHandling
{
    static void Main(string[] args)
    {
      
        bool continueLoop = true;
        
        do
        {
            try
            {
                Console.WriteLine("Enter the first integer to add:");
                int a = Int32.Parse(Console.ReadLine());
                Console.WriteLine("Enter second integer to add:");
                int b = Int32.Parse(Console.ReadLine());
                int sum = a + b;

               if(a < 0)
                {
                    Console.WriteLine("Please enter a non-negative integer:", a);
                    Console.ReadLine();
                } 
                if (b < 0)
                {
                    Console.WriteLine("\nPlease enter a non-negative integer:", b);
                    Console.ReadLine();

                }
                      
               
                
                    
                    Console.WriteLine("\nTotal is {0}", sum);
                continueLoop = false;

            }//end try

            catch (FormatException formatException)
            {
                Console.WriteLine("\n" + formatException.Message);
                Console.WriteLine("Please enter an integer and try again. \n");

            }//end catch
        }
        while (continueLoop);   //end do-while


        Console.WriteLine("\nPress enter to exit.");
        Console.ReadLine();
    }
}

Posted 24-Jan-17 9:32am

OfficialSub0

Updated 24-Jan-17 18:25pm

v3

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Comments

[no name] 24-Jan-17 15:50pm

Use TryParse

Philippe Mori 25-Jan-17 12:26pm

Do you really want to ask both numbers again if one is negative?

2 solutions

Solution 2

public int GetValue(string prompt)
   {
   int value;
   while (true)
      {
      Console.WriteLine(prompt);
      if (int.TryParse(Console.ReadLine, out value))
         {
         break;
         }
      }
   return value;
   }

Posted 24-Jan-17 10:14am

OriginalGriff

Comments

Philippe Mori 25-Jan-17 12:23pm

Validation is missing to ensure positive number...

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Peter Leow · Accepted Answer · 2017-01-24T18:25:00

Solution 3

Try this:

using System;

public class Program
{
	public static void Main()
	{
		int input;
		bool isInteger = false;
		do
		{
			Console.WriteLine("Input a positive integer:");
			isInteger = Int32.TryParse(Console.ReadLine(), out input);
		}
		while (!(isInteger && input >= 0));
		Console.WriteLine("You have input " + input);
	}
}

Posted 24-Jan-17 18:25pm

Peter Leow

Comments

Philippe Mori 25-Jan-17 12:24pm

Should be a function as in solution 2...

OfficialSub0 25-Jan-17 14:02pm

Enter the first integer to add:
-2
Enter second integer to add:
5
Input a positive integer:
2345677
You have input 2345677

Total is 3

Press enter to exit.

This is the output in the command prompt. Sorry if i didn't clarify, but I do indeed want to keep formatException to catch any input that's not an integer (ex:"hello").

Philippe Mori 25-Jan-17 14:08pm

If you use your original code and both solutions 2 and 3, then it is trivial to solve your problem... If you expect us to give a complete solution, then you won't learn much and not improve yourself.

OfficialSub0 25-Jan-17 15:57pm

Thanks I understand that part now! If I may ask, does the TryParse method allow for use of formatException because it skips it?