How can I check if a string is a number?

Question

I\'d like to know on C# how to check if a string is a number (and just a number).

Example :

141241   Yes
232a23   No
12412a   No

an

Answer 1

Many datatypes have a TryParse-method that will return true if it managed to successfully convert to that specific type, with the parsed value as an out-parameter.

In your case these might be of interest:

http://msdn.microsoft.com/en-us/library/system.int32.tryparse.aspx

http://msdn.microsoft.com/en-us/library/system.decimal.tryparse.aspx

Answer 2

Regex.IsMatch(stringToBeChecked, @"^\d+$")

Regex.IsMatch("141241", @"^\d+$")  // True

Regex.IsMatch("232a23", @"^\d+$")  // False

Regex.IsMatch("12412a", @"^\d+$")  // False

Answer 3

Perhaps you're looking for the int.TryParse function.

http://msdn.microsoft.com/en-us/library/system.int32.tryparse.aspx

Answer 4

Try This

here i perform addition of no and concatenation of string

 private void button1_Click(object sender, EventArgs e)
        {
            bool chk,chk1;
            int chkq;
            chk = int.TryParse(textBox1.Text, out chkq);
            chk1 = int.TryParse(textBox2.Text, out chkq);
            if (chk1 && chk)
            {
                double a = Convert.ToDouble(textBox1.Text);
                double b = Convert.ToDouble(textBox2.Text);
                double c = a + b;
                textBox3.Text = Convert.ToString(c);
            }
            else
            {
                string f, d,s;
                f = textBox1.Text;
                d = textBox2.Text;
                s = f + d;
                textBox3.Text = s;
            }
        }

Answer 5

int.TryPasrse() Methode is the best way so if the value was string you will never have an exception , instead of the TryParse Methode return to you bool value so you will know if the parse operation succeeded or failed

string yourText = "2";
int num;
bool res = int.TryParse(yourText, out num);
if (res == true)
{
    // the operation succeeded and you got the number in num parameter
}
else
{
   // the operation failed
}

Answer 6

string str = "123";
int i = Int.Parse(str);

If str is a valid integer string then it will be converted to integer and stored in i other wise Exception occur.