How would i check if the value entered is an int in if statement?

Question

I would've used Try Parse but i don't want to use the value, i just want to check if its an integer or not.

if (txtCardNumber.TextLength < 16 || txtCardNumber.TextLength > 16)
            {
                MessageBox.Show("Please ensure that your card number is 16 digits long and in the correct format!");
            }

Answer 1

You don't need to declare a var with TryParse, do it like this

Add this class to your project (makes it reusable), it's known as a language extension.

public static class StringExtensions    
{
    public static bool IsNumeric(this string text) => double.TryParse(text, out _);

}

Use it

if (txtCardNumber.Text.IsNumeric())
{

}

Using double indicates it can represent an int, double essentially a number

Answer 2

You do not say what txtCardNumber is but if it is a text box then I assume the relevant string is txtCardNumber.Text. If so then if (txtCardNumber.Text.All(Char.IsDigit)) will be true if all characters are a digit and false otherwise.