Beginner code, something is not right. If and else if statement (C#)

Question

I am learning how to program so please be nice. :)

I have this error running the code:

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll Additional information: Input string was not in a correct format.

When I type "screw you, don't tell me what to do!". When I delete the whole insult part of the code, it's working flawlessly. What am I doing wrong?

namespace ConsoleApplication6 
{
    class Program
    {
        static void Main(string[] args)
        {
            int numero1 = 5; //Declaring first variable
            int numero2 = 5; //Declaring second variable

            Console.WriteLine ("What is the answer of " + numero1 + " x " + numero2); //Asking question to the user

            int answer = Convert.ToInt32(Console.ReadLine()); //Converting the "answer" to integral variable
            string insult = Console.ReadLine(); //The user enter his insult          

            if (answer == 25) //If the answer is 25
            {
                Console.WriteLine("Good answer!"); //This message appears            
            }
            else if (insult == "screw you, don't tell me what to do!") //If the user insult me
            {
                Console.WriteLine("Wow buddy, gotta check that language!"); //The user receives this message              
            }
            else
            {
                Console.WriteLine("Dude...what?"); //If the user write anything else, he gets this message
            }
            Console.ReadKey();
        }
    } 
}

`int answer = Convert.ToInt32(Console.ReadLine());` make sure you enter a numeric characters only. — kevintjuh93, Oct 02 '15 at 08:00
Do you understand that your code is trying to read *two* lines of user input? It's converting the first to a number, and then expecting the second to be an insult. Is that what you intended? — Jon Skeet, Oct 02 '15 at 08:01
get only one input. then `TryParse`. if it succeed show Good answer. otherwise check for other sentences. — M.kazem Akhgary, Oct 02 '15 at 08:10

score 1 · Answer 1 · answered Oct 02 '15 at 08:32

Do like this:

        int numero1 = 5; //Declaring first variable
        int numero2 = 5; //Declaring second variable

        Console.WriteLine ("What is the answer of " + numero1 + " x " + numero2); //Asking question to the user

        string answer = Console.ReadLine(); //Converting the "answer" to integral variable


        if (answer == "25") //If the answer is 25
        {
            Console.WriteLine("Good answer!"); //This message appears            
        }
        else if (answer == "screw you, don't tell me what to do!") //If the user insult me
        {
            Console.WriteLine("Wow buddy, gotta check that language!"); //The user receives this message              
        }
        else
        {
            Console.WriteLine("Dude...what?"); //If the user write anything else, he gets this message
        }
        Console.WriteLine("Press any key to close the application");
        Console.ReadKey();

This is a simple change that makes your code easier to understand, hopefully. You are already "hardcoding" the results so by putting 25, in a string, does not make your code less good.

Thank you Marcus. I could have done it like that but I wanted to spice things up. — Sam Burbank, Oct 02 '15 at 08:54

score 0 · Answer 2 · answered Oct 02 '15 at 08:02

use int.TryParseas below, if user enter non integer value your program will fail

Console.WriteLine ("What is the answer of " + numero1 + " x " + numero2);
string keyboardInput = Console.ReadLine();
int answer;
while (!int.TryParse(keyboardInput, out answer)) {
    Console.WriteLine("Invalid input, try again.");
    keyboardInput = Console.ReadLine();
}
// now read the insult
string insult = Console.ReadLine();

since you need two inputs you need to click enter after entering answer, then again you can type the insult and hit enter

Beginner code, something is not right. If and else if statement (C#)

2 Answers2