Throw a format exception C#

Question

I'm trying to throw a format exception in the instance someone tries to enter a non-integer character when prompted for their age.

        Console.WriteLine("Your age:");
        age = Int32.Parse(Console.ReadLine());

I'm unfamiliar with C# language and could use help in writing a try catch block for this instance.

Thanks very much.

Columniation

Int32.Parse will throw a FormatException if a non-numeric string is passed to it - your code looks like it does what you want it to? – Sympathetic

Do you mean you're trying to catch a format exception? – Roanne

Int32.Parse could return three different exceptions – Aerophobia

this should help you msdn.microsoft.com/en-us/library/ms173160(v=vs.80).aspx – Zacek

Answer 1

That code will already throw an FormatException. If you mean you want to catch it, you could write:

Console.WriteLine("Your age:");
string line = Console.ReadLine();
try
{
    age = Int32.Parse(line);
}
catch (FormatException)
{
    Console.WriteLine("{0} is not an integer", line);
    // Return? Loop round? Whatever.
}

However, it would be better to use int.TryParse:

Console.WriteLine("Your age:");
string line = Console.ReadLine();
if (!int.TryParse(line, out age))
{
    Console.WriteLine("{0} is not an integer", line);
    // Whatever
}

This avoids an exception for the fairly unexceptional case of user error.

Hernia

I'm a little confused by this line: if (!int.TryParse(line, out age) – Columniation

@user1513637: In what way? int.TryParse returns whether or not it was successful, and store the result in the out parameter. See the documentation for details. – Hernia

Answer 2

What about this:

Console.WriteLine("Your age:");
try
{    
     age = Int32.Parse(Console.ReadLine());
}
catch(FormatException e)
{
    MessageBox.Show("You have entered non-numeric characters");
   //Console.WriteLine("You have entered non-numeric characters");
}

Lindblad

Answer 3

No need to have a try catch block for that code:

Console.WriteLine("Your age:");
int age;
if (!Integer.TryParse(Console.ReadLine(), out age))
{
    throw new FormatException();
}

Aerophobia

Answer 4

you can do this...

int age;

Console.WriteLine("Your age:"); age=Conver.ToInt32(Console.Readline());

//@Erfunll

Coit

The original author was asking for help on how to write a try/catch. Your answer might be improved by showing him how to do this. – Ashbey

Hi and welcome to Stack Overflow! Please take the tour. Thanks for answering but can you also add an explanation on how your code solves the issue? Also, check the help center for info on how to format code. – Corpuscle

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. – Dialyse