Re: C # + Regex help (for a newbie) - C# Discussion Boards

Damian Bz27-Dec-17 4:16

27-Dec-17 4:16

Hi All,
I have just started to self learn C#, and have written my first basic application.

It is pretty simple,it has 8 text boxes that accept numerical values, which it then does some calculations on and displays 3 textbox outputs.

I worked out the calculations using Excel then translated that into C# and it all works ! as long as no one puts the wrong numbers in !

What I am trying to achieve is to validate four types of inputs:

One set of text boxes can accept whole numbers and no letters from 1 to 1000
One set of text boxes can accept whole numbers and no letters from 1 to 100

On these two types of textboxes, I have this code:

private void totalsize_TextChanged(object sender, EventArgs e)
{
    if (System.Text.RegularExpressions.Regex.IsMatch(totalsize.Text, "[^0-9]"))
    {
        MessageBox.Show("Please enter only full numbers i.e. 70  NOT  65.5");
        totalsize.Text = totalsize.Text.Remove(totalsize.Text.Length - 1);
        totalsize.Focus();
    }
}

From what I understand the regex is basically checking that the first character is not non numerical, so it sort of does one part of what I needed it to do.

I then have another input that I want to be able to validate: numbers only again, but only allow a single number with a single decimal point i.e. 7.2 3.6 but not 7.22222 or 70 so anything from 1 to 9 including a single decimal point.

private void nicstrength_TextChanged(object sender, EventArgs e)
{
        if (System.Text.RegularExpressions.Regex.IsMatch(nicstrength.Text, "insert jibberish here"))
        {
            MessageBox.Show("Please enter only numbers.");
            nicstrength.Text = nicstrength.Text.Remove(nicstrength.Text.Length - 1);
            nicstrength.Focus();
        }

    }

The last input I want to validate will be again numbers only but from 0.n to 2.n , so 0.6 or .6 - 1.2 or 2 (2 or above will probably not ever get entered)

private void finalnicstrength_TextChanged(object sender, EventArgs e)
{
    if (System.Text.RegularExpressions.Regex.IsMatch(finalnicstrength.Text, @"^[1-9]\d*(\.\d+)?$"))
    {
        MessageBox.Show("Please enter only numbers.");
        finalnicstrength.Text = finalnicstrength.Text.Remove(finalnicstrength.Text.Length - 1);
        finalnicstrength.Focus();
    }
}

I have tried zillions of combinations found on the net, plus I've used a couple of regex generators (frustratingly, some say a regex works and some say it doesn't - but none work when I put them into my code !)
I've learnt that I either need to put an @ in front of it, or use double \\ or whatever for C# to know what it is, but i'm just really struggling with this.
I am dyslexic (not looking for sympathy) so looking at regex makes my head explode !

Please can someone help me with the last two types at the very least, I know the top two are not 100% correct, but they at least stop letters and decimal points being entered.

Many thanks for reading, and even more for helping me ! Smile | :)

Damian