Textbox validation in C# Winforms - Should allow only numerics between 1-100

Question

Hello Sorry its a simple question, but would appreciate if someone can guide me with the code. I have say 50 textboxes in my Winform. All should allow only numeric values and that too between 1-100 only. How should I ensure this validation?

My thoughts was using e.Keychar in keypress event using Ascii values to restrict users to type only numerics. Also, probably I can ensure this validation in Set in the property? But I don't know if I am correct and also don't know right code. Please help me.

Habib · Accepted Answer · 2013-11-08 14:43:39Z

5

Use NumericUpDown instead of normal TextBox box with validation.

A NumericUpDown control contains a single numeric value that can be incremented or decremented by clicking the up or down buttons of the control. The user can also enter in a value, unless the ReadOnly property is set to true.

You can specify the minimum and maximum numbers, it will allow the user to enter numbers between 1 and 100 and also let them use up and down buttons.

EDIT: If you want to do it through code then you can try something like in KeyPress event of your TextBox:

private void yourTextBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar)
        && !char.IsDigit(e.KeyChar))
    {
        e.Handled = true;
    }
}

The above can be improved to access . for decimal numbers, but I guess you got the idea.

edited Nov 8, 2013 at 14:43

answered Nov 8, 2013 at 14:24

Habib

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5 Comments

Jasmine Over a year ago

@Habib: Thanks :( I got my interview flucked :( Interviewer confused me and I just told what I wrote above :( He was again and again asking me. I never got an idea of NumericUpDOwn. Thank you Habib. But if I have to ask you how to do custom validation, any pointers for my situation please? A small code snippet would help me understand

Habib Over a year ago

@Divine, just updated my answer with the code, you can do that in ` KeyPress event like in the answer, it can definitely be improved, but just wanted to give you an idea

Jasmine Over a year ago

@Habib: Thank you so much. However the above code will allow values beyond 100? Or is that something that is homework for me? :) I am happy to do that if so. Well anyway, its a learning, it can be useful for my future interviews

Habib Over a year ago

@Divine, you can check the ascii values to see if it is between 1 and 100, you can parse it to int and see if it is between 1 and 100, many ways...., its for you to figure it out,

Jasmine Over a year ago

@Habib: Thank you so much, I will do it today itself and learn it :) :) Your input helped me a lot.... :) Cheers

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