Question

I used from Error Provider in C# winform. in my form have textbox. error provider checked it that it contain two number. it means that input is digit and number of digit is two number. when input is 2 char , error provider is worked but when input is char and digit, error provider didn’t worked.
please check my code.

 private void textbox1_Leave(object sender, EventArgs e)
        {
            string text = textbox1.Text;
            bool hasDigit = false;

                foreach (char letter in text)
                {
                    if (char.IsDigit(letter))
                    {
                        hasDigit = true;
                        break;
                    }
                }

            // Call SetError or Clear on the ErrorProvider.
            if (!hasDigit )
            {
                errorProvider1.SetError(textbox1, "Please enter digit");
            }
            else if(hasDigit) 

            {

                if (text.TextLength != 2)
                {
                    errorProvider1.SetError(textbox1, "Number of digit is two number");
                }
                else
                errorProvider1.Clear();
            }
        }

Answer 1

So you want to ensure that all chars are digits. But you’re checking only the first, if that’s a digit you’re breaking the loop:

foreach (char letter in text)
{
    if (char.IsDigit(letter))
    {
        hasDigit = true;
        break;
    }
}

Instead you could use Linq for this. Enumerable.All is made for this purpose:

bool allDigits = text.All(c => Char.IsDigit(c));

(but maybe i’m totally off the track since the question is not so clear imho)