how to validate the texbox using c#

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I am developing a windows application where i need to validate the textbox which can accept only numeric value, single dot(.), and backspace and delete key. for this i am writing this code

C#

if ((e.KeyChar=='.' && textBox1.Text.IndexOf('.')>-1) || char.IsLetter(e.KeyChar) || char.IsPunctuation(e.KeyChar) || char.IsSymbol(e.KeyChar))
           {
               e.Handled = true;
           }

but it is not accepting the dot(.) because (.) comes under punctuation. please help me
to do this which accepts the (.) except others punctuation.

Posted 7-Sep-12 8:14am

Imteyaz Ahmed

Updated 7-Sep-12 8:15am

Wes Aday

v2

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5 solutions

Solution 3

It would be a little simpler:

if ((e.KeyChar=='.' && textBox1.Text.IndexOf('.')>-1) || ! e.KeyChar==Keys.Delete && ! e.KeyChar==Keys.Back || !  char.IsDigit(e.KeyChar))
{
  e.Handled = true;
}

Posted 7-Sep-12 9:24am

Clifford Nelson

v2

Solution 4

hiii,
try this

C#

if (  char.IsLetter(e.KeyChar) || char.IsPunctuation(e.KeyChar) || char.IsSymbol(e.KeyChar))
           {
               if ((e.KeyChar == '.' && textBox1.Text.IndexOf('.')>-1 ))
               {
                   e.Handled = true;
               }
           }

Posted 7-Sep-12 18:23pm

Ganesh Nikam

Solution 5

if ((e.KeyChar == '.' && textBox1.Text.IndexOf('.') > -1) || char.IsLetter(e.KeyChar) || (e.KeyChar >= (char)33 && e.KeyChar <= (char)45) || char.IsSymbol(e.KeyChar) || (e.KeyChar >= (char)58 && e.KeyChar <= (char)64) || (e.KeyChar >= (char)91 && e.KeyChar <= (char)96) || (e.KeyChar >= (char)123 && e.KeyChar <= (char)126) || e.KeyChar=='/')
{
e.Handled = true;
}

Posted 7-Sep-12 21:24pm

Imteyaz Ahmed

Solution 2

But your code is correct.

C#

if ((e.KeyChar=='.' && textBox1.Text.IndexOf('.')>-1) || char.IsLetter(e.KeyChar) || char.IsPunctuation(e.KeyChar) || char.IsSymbol(e.KeyChar))
            {
                e.Handled = true;
            }

You are checking the char is . in the first condition and returing true.Why it is going for the next Or condition.

Posted 7-Sep-12 9:08am

Ashraff Ali Wahab

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OriginalGriff · Accepted Answer · 2012-09-07T08:21:00

Solution 1

Why use a textbox?
Use a NumericUpDown instead - it looks like a textbox (with an up and a down arrow), it works like a text box, but it has the validation already built in.

Posted 7-Sep-12 8:21am

OriginalGriff

Comments

Imteyaz Ahmed 7-Sep-12 14:25pm

i cannot use numeric updown key. i need validation on textbox.