C#•2y ago

❔ Can not figure out a way to make my code repeat until you type a valid input

im having a hard time figuring out how to make my code repeat until you enter a number and if you enter a letter or some other character it will just repeat itself im also kinda new to this so please dont butcher me

namespace CSLearning
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Enter your type of equation(+, -, *, /): ");
            string typeOfEquation = Console.ReadLine();
            if (typeOfEquation.Contains('+'))
            {
                double num1 = 0;
                double num2 = 0;
                Console.Write("Enter your first adden: ");
                string adden1 = Console.ReadLine();
                Console.Write("Enter your second adden: ");
                string adden2 = Console.ReadLine();
                num1 = Convert.ToDouble(adden1);
                num2 = Convert.ToDouble(adden2);
                Console.WriteLine("The awsnwer to your equation is " + num1 + num2);
            }

            Console.ReadLine();
        }

    }
}

namespace CSLearning
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Enter your type of equation(+, -, *, /): ");
            string typeOfEquation = Console.ReadLine();
            if (typeOfEquation.Contains('+'))
            {
                double num1 = 0;
                double num2 = 0;
                Console.Write("Enter your first adden: ");
                string adden1 = Console.ReadLine();
                Console.Write("Enter your second adden: ");
                string adden2 = Console.ReadLine();
                num1 = Convert.ToDouble(adden1);
                num2 = Convert.ToDouble(adden2);
                Console.WriteLine("The awsnwer to your equation is " + num1 + num2);
            }

            Console.ReadLine();
        }

    }
}

11 Replies

Angius•2y ago

Use a loop A while loop, most commonly And $tryparse to check if the entered value is actually a number. And if so, to get the parsed value out

MODiX•2y ago

The TryParse pattern is considered best practice of parsing data from a string: - a TryParse method returns true or false to inform you if it succeeded or not, so you can use it directly in a condition, - since C# 7 you can declare a variable that will be used as an out argument inline in an argument list, - it forces you to check if the out argument contains valid data afterwards, Avoid: Convert.ToInt32 — it's a bad choice for parsing an int. It exists only for backwards compatibility reasons and should be considered last resort.

return Convert.ToInt32(null); //returns 0. null should not be considered as 0 ever
return Convert.ToInt32("asdf"); //throws FormatException

return Convert.ToInt32(null); //returns 0. null should not be considered as 0 ever
return Convert.ToInt32("asdf"); //throws FormatException

(Note: Convert does contain useful conversion methods: To/FromBase64String, To/FromHexString, ToString(X value, int toBase), ToX(string? value, int fromBase)) Avoid: int.Parse — you have to use a try/catch statement to handle invalid input, which is a less clean solution.

var number = int.Parse("abc"); //throws FormatException
var number = int.Parse(""); //throws FormatException

var number = int.Parse("abc"); //throws FormatException
var number = int.Parse(""); //throws FormatException

Use int.TryParse https://docs.microsoft.com/en-us/dotnet/api/system.int32.tryparse?view=net-5.0#System_Int32_TryParse_System_String_System_Int32__

if (int.TryParse(someInput, out var result))
{
  Console.WriteLine($"Thanks for giving me the following number: {result}!");
}
else
{
  Console.WriteLine("You didn't give me a valid number :c");
}

if (int.TryParse(someInput, out var result))
{
  Console.WriteLine($"Thanks for giving me the following number: {result}!");
}
else
{
  Console.WriteLine("You didn't give me a valid number :c");
}

Int32.TryParse Method (System)

Converts the string representation of a number to its 32-bit signed integer equivalent. A return value indicates whether the operation succeeded.

ThisIanOP•2y ago

how do I add the while loop in the code

Angius•2y ago

Just... do Write it

ThisIanOP•2y ago

huh?

Angius•2y ago

Adding a while loop is no different than adding any other piece of code Just stroke the keys on your keyboard to input proper symbols that make up valid syntax

Aaron•2y ago

there's a learning module on while loops if you need it

Aaron•2y ago

https://learn.microsoft.com/en-us/training/modules/csharp-do-while/

Add looping logic to your code using the do-while and while stateme...

Use the do-while and while statements to iterate as long as a Boolean expression evaluates to true.

ThisIanOP•2y ago

while (adden1 != double) is the only thing that comes to my mind and it doesnt work

Angius•2y ago

I told you to use TryParse() since it returns a boolean The bot even posted more explanation

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Can not figure out a way to make my code repeat until you type a valid input