C# testing to see if a string is an integer?

Question

I\'m just curious as to whether there is something built into either the C# language or the .NET Framework that tests to see if something is an integer

if (x         


        

Answer 1

private bool isNumber(object p_Value)
    {
        try
        {
            if (int.Parse(p_Value.ToString()).GetType().Equals(typeof(int)))
                return true;
            else
                return false;
        }
        catch (Exception ex)
        {
            return false;
        }
    }

Something I wrote a while back. Some good examples above but just my 2 cents worth.

Answer 2

I've been coding for about 2 weeks and created a simple logic to validate an integer has been accepted.

    Console.WriteLine("How many numbers do you want to enter?"); // request a number
    string input = Console.ReadLine(); // set the input as a string variable
    int numberTotal; // declare an int variable

    if (!int.TryParse(input, out numberTotal)) // process if input was an invalid number
    {
        while (numberTotal  < 1) // numberTotal is set to 0 by default if no number is entered
        {
            Console.WriteLine(input + " is an invalid number."); // error message
            int.TryParse(Console.ReadLine(), out numberTotal); // allows the user to input another value
        }

    } // this loop will repeat until numberTotal has an int set to 1 or above

you could also use the above in a FOR loop if you prefer by not declaring an action as the third parameter of the loop, such as

    Console.WriteLine("How many numbers do you want to enter?");
    string input2 = Console.ReadLine();

    if (!int.TryParse(input2, out numberTotal2))
    {
        for (int numberTotal2 = 0; numberTotal2 < 1;)
        {
            Console.WriteLine(input2 + " is an invalid number.");
            int.TryParse(Console.ReadLine(), out numberTotal2);
        }

    }

if you don't want a loop, simply remove the entire loop brace

Answer 3

Use the int.TryParse method.

string x = "42";
int value;
if(int.TryParse(x, out value))
  // Do something

If it successfully parses it will return true, and the out result will have its value as an integer.

Answer 4

For Wil P solution (see above) you can also use LINQ.

var x = "12345";
var isNumeric = !string.IsNullOrEmpty(x) && x.All(Char.IsDigit);

Answer 5

If you just want to check type of passed variable, you could probably use:

    var a = 2;
    if (a is int)
    {
        //is integer
    }
    //or:
    if (a.GetType() == typeof(int))
    {
        //is integer
    }

Answer 6

Maybe this can be another solution

try
{
    Console.Write("write your number : ");
    Console.WriteLine("Your number is : " + int.Parse(Console.ReadLine()));
}
catch (Exception x)
{
    Console.WriteLine(x.Message);
}
Console.ReadLine();