TextBox Validation In Windows Forms

[Normann]

Hallo

I need some help with textboxes, I have a textbox that I need to test if it contains numbers only, I know I can use a masked textbox but it just do’s not fit my use, I have some of the code I need which you can see below here, the part I need is in the second line.

Language: C#
Platform: WinXP
Programming software: VS2005
Type: Windows Forms

 
 
 if (textBoxAddBook_Year.Text.Length == 4)
   if (textBoxAddBook_Year.Text ==  Missing!!!)    
     if (Convert.ToInt32(textBoxAddBook_Year.Text) >= 1600)
       if (Convert.ToInt32(textBoxAddBook_Year.Text) <= DateTime.Now.Year)
          { varYearOK = true; }
 
 

As you can see I need to check if the text in the textbox is numbers only before I check if the year is correct.

NormannTheDane

[mzmishra]

There is a article on this.You may got some idea from that
http://www.codeproject.com/useritems/Usertextboxcontrol.asp

[SammyB]

Add an ErrorProvider control to your form and use the Validated event:

private void textBox1_Validated(object sender, EventArgs e)
{
    string msg = "";
    int iYear;
    if (textBox1.Text == "")
        msg = "Must be completed.";
    else if (textBox1.Text.Length != 4)
        msg = "Use 4 digit date.";
    else if (!int.TryParse(textBox1.Text, out iYear))
        msg = "Invalid year.";
    else if ((iYear < 1600) || (iYear > DateTime.Now.Year))
        msg = "Year must be greater than 1600";
    errorProvider1.SetError(textBox1, msg);
}
 

See the ErrorProvider help, http://msdn2.microsoft.com/en-us/lib...er(VS.80).aspx for a longer example.

[phvfl]

Hi Normann,

You can accomplish the first two if conditions using one regular expression. You will need to add a Using statement to include System.Text.RegularExpressions and then the following will define a regular expression:

Regex reg = new Regex("^[0-9]{4}$");
 

The content of the square brackets is the characters to match (0-9 is all numbers).

The number in the curly brackets is the number of characters to match so this would match with 4 characters.

The "^" matches with the start of the string and the "$" with the end of the string, these are used so that a string of 5 or more numbers is not matched with.

You can then test for the match using the IsMatch member of the Regex object, the return is True if a match is found so your code could be written as:

  if (reg.IsMatch(textBoxAddBook_Year.Text)){
    Int32 intYr = Convert.ToInt32(textBoxAddBook_Year.Text);
      if (intYr>=1600 && intYr <= DateTime.Now.Year){
      varYearOK = true; 
    }
  } 
 

I have also combined the next two if conditions as it looks tidier to read and only one conversion to an integer needs to be made.

[Normann]

Ok ask a question, and not only get an answer to the question but also get a solution to three other problems, now that is what I like.

Thank you all for your help.

NormannTheDane