C#•7d ago

✅ Try catch exception.

What is the best way to keep doing a do while loop if an exception has been caught? Atm if I create the exception code within the do while loop the variables are not then declared even though they are The following example works but exits out of the do while loop. variables try{ do{code} while{code} } catch(Exception){code}

31 Replies

mg•7d ago

switch them around try/catch inside the loop, instead of the loop inside the try/catch not sure what you mean about the variables not being declared "are not then declared even though they are" doesn't quite make sense

77_105_114_111OP•7d ago

I tried your suggestion but some of the variables are bugged

mg•7d ago

so let's work with that what do you mean when you say some variables are bugged

77_105_114_111OP•7d ago

on the variable named option, it says use of unassigned variable 'option'

mg•7d ago

you'll have to share the code so i can see the variable you're talking about

77_105_114_111OP•7d ago

mg•7d ago

can't give a full answer if you only show me half the code $code

MODiX•7d ago

To post C# code type the following: ```cs // code here ``` Get an example by typing $codegif in chat For longer snippets, use: https://paste.mod.gg/

77_105_114_111OP•7d ago

//internal class Program
{
    private static void Main(string[] args)
    {
        ushort option;
        long additionNum1;
        long additionNum2;
        long result;

        do
        {
            try
            {

                Console.WriteLine("Welcome to the custom calculator.");
                Console.WriteLine("----------------------------------------------");
                Console.WriteLine("1. Press 1 for + Addition: ");
                Console.WriteLine("2. Press 2 for - Subraction: ");
                Console.WriteLine("3. Press 3 for * Multiplication: ");
                Console.WriteLine("4. Press 4 for / Division: ");
                Console.WriteLine("5. Press 5 for % Modulo: ");
                Console.WriteLine("6. Press 6 for ² Square root: ");
                Console.WriteLine("7. Press 7 to exit calculator: ");
                Console.WriteLine();


                option = ushort.Parse(Console.ReadLine());

                if (option == 1)
                {

                    Console.WriteLine();
                    Console.WriteLine("Enter the addition numbers: ");
                    additionNum1 = long.Parse(Console.ReadLine());
                    additionNum2 = long.Parse(Console.ReadLine());
                    result = additionNum1 + additionNum2;
                    Console.WriteLine(additionNum1 + " + " + additionNum2 + " = " + result);
                    Console.WriteLine();

                }
                Console.WriteLine();
            }
            catch (Exception)
            {
                Console.WriteLine("Invalid input.");
            }
        }

        while (option != 7);



        Console.WriteLine("Thank you for using the custom calculator.");
        Console.ReadKey();
    }
}

//internal class Program
{
    private static void Main(string[] args)
    {
        ushort option;
        long additionNum1;
        long additionNum2;
        long result;

        do
        {
            try
            {

                Console.WriteLine("Welcome to the custom calculator.");
                Console.WriteLine("----------------------------------------------");
                Console.WriteLine("1. Press 1 for + Addition: ");
                Console.WriteLine("2. Press 2 for - Subraction: ");
                Console.WriteLine("3. Press 3 for * Multiplication: ");
                Console.WriteLine("4. Press 4 for / Division: ");
                Console.WriteLine("5. Press 5 for % Modulo: ");
                Console.WriteLine("6. Press 6 for ² Square root: ");
                Console.WriteLine("7. Press 7 to exit calculator: ");
                Console.WriteLine();


                option = ushort.Parse(Console.ReadLine());

                if (option == 1)
                {

                    Console.WriteLine();
                    Console.WriteLine("Enter the addition numbers: ");
                    additionNum1 = long.Parse(Console.ReadLine());
                    additionNum2 = long.Parse(Console.ReadLine());
                    result = additionNum1 + additionNum2;
                    Console.WriteLine(additionNum1 + " + " + additionNum2 + " = " + result);
                    Console.WriteLine();

                }
                Console.WriteLine();
            }
            catch (Exception)
            {
                Console.WriteLine("Invalid input.");
            }
        }

        while (option != 7);



        Console.WriteLine("Thank you for using the custom calculator.");
        Console.ReadKey();
    }
}

mg•7d ago

and what's the exact error it's giving you?

77_105_114_111OP•7d ago

The error is on this line of code while (option != 7);

mg•7d ago

right, but what exactly does the error say

77_105_114_111OP•7d ago

use of unassigned local variable 'option'

mg•7d ago

ok, so, the problem is that, although you know Console.WriteLine() won't throw an exception, the compiler doesn't let's pretend that every time the loop runs, an exception is thrown before option = ushort.Parse(Console.ReadLine()) is reached then option will never get a value assigned to it

77_105_114_111OP•7d ago

mg•7d ago

so the solution is just to initialize option to something

77_105_114_111OP•7d ago

updated ushort option; to ushort option = 0; it's working now, thank you

mg•7d ago

sure thing

Adam Vincent•7d ago

no need to bother with ushort in .NET just use int ushort gets expanded to 32bit anyways, and integer math is faster. also, generally speaking, exceptions are for exceptional circumstances. with your console app example, a user entering a bad option wouldn't generally be considered exceptional.

77_105_114_111OP•7d ago

ushort is 2 bytes & uint is 4 bytes plus I don't need that many numbers for the option menu

Cattywampus•7d ago

ushort is fine

mg•6d ago

this refers more to throwing exceptions. they could (and should) use TryParse(), but catching an exception isn't strictly wrong

Adam Vincent•6d ago

right! we read the same thing from different perspectives. It is fine. But in general, int is the framework default convention. I prefer to stick to convention.

77_105_114_111OP•6d ago

seems like a bit of a hassle trying to get TryParse() to work with user input & switch case

mg•6d ago

TryParse() really only needs to be in the input portion combining it with continue should get you something similar to what you have now, functionality-wise

77_105_114_111OP•6d ago

if the user input is a string data type then it does not work with switch case because switch case only excepts numeric data. I guess the only good time to use TryParse() is when working with if else statements

mg•6d ago

switch statements in C# accept way more than numbers

77_105_114_111OP•6d ago

so instead of case 1: case: 2 we can have case stringName: case stringName2? Ok I understand instead of case: 1 we can change it to case "1":

mg•6d ago

yep and then you don't need to parse to an integer at all you can just have a default: case that handles invalid input

77_105_114_111OP•6d ago

I created 2 custom calculator apps one with if statements & Try Catch. The other with switch case & TryParse(), 3 kilo bytes difference, not much but then again if I were to use the TryParse() with a much bigger app then it adds up Thanks again for the support, cheers.

mg•6d ago

sure thing! i'd advise that source code size, binary size, and lines of code aren't very good indicators of complexity. with modern storage, unless you're working in a constrained environment like a microcontroller, don't worry too much about size

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