How to test if an Integer is within a range while using a TextBox in C#

Question

I'm building a Windows Form in C# and I'm trying to test whether the users input is between 1 and 7 (Representing the number of days in a week, that a movie can be rented). If the test returns false, then I want to output an error message. I'm using a text box to get the users input. The problem is, I keep receiving this error when running the program :

System.FormatException was unhandled

HResult=-2146233033

Message=Input string was not in a correct format.

Can somebody please, tell me what I am doing wrong. Thank you in advance.

Here is the code I have written..

 private void nightsRentedTextBox_TextChanged_1(object sender, EventArgs e)
    {
        Boolean inputBoolean = true;
      
        if (int.Parse(nightsRentedTextBox.Text) < 1)
        {
            MessageBox.Show("Enter a number between 1 and 7", "INPUT ERROR",
            MessageBoxButtons.OK, MessageBoxIcon.Error);
            inputBoolean = false;
        }

to start with use TryParse().....

Mitch Wheat
– Mitch Wheat

2016-11-18 03:25:43 +00:00
Commented Nov 18, 2016 at 3:25 — Mitch Wheat
– Mitch Wheat, Commented Nov 18, 2016 at 3:25

Mohit S · Accepted Answer · 2016-11-18 03:32:35Z

1

You should use TryParse instead.

int nightsRented;
bool res = int.TryParse(nightsRentedTextBox.Text, out nightsRented);
if (res == false)
{
  // String is not a number.
}

or you can use it like

int nightsRented;
if (int.TryParse(nightsRentedTextBox.Text, out nightsRented);)
{
    if (nightsRented >= 1 || nightsRented <= 7)
    {
        MessageBox.Show("Enter a number between 1 and 7", "INPUT ERROR",
        MessageBoxButtons.OK, MessageBoxIcon.Error);
        inputBoolean = false;
    }
}

edited Nov 18, 2016 at 3:32

answered Nov 18, 2016 at 3:25

Mohit S

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2 Comments

Yanga Over a year ago

Can use if (Enumerable.Range(1, 7).Contains(NumberOfNights)) too.

Mohit S Over a year ago

Happy to help. :) @CaseySmith

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