C# .NET - how to validate textbox to accept only characters

Asked By v k on 18-Aug-11 02:46 AM

hi...
I am using RAD Text box..I want to check that if user is entering the value in text box it should only character allow spacing its OK. I want it through JavaScript and should display the message box for user that should" enter character only" all this functionality should happen on click of Submit Button...
thanks!!!!!

Anoop S replied to v k on 18-Aug-11 02:49 AM

i am assuming you want to accept only alphabets. and not any special characters, if thats the case you can use the below sample. hope this helps

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:RegularExpressionValidator

ID="RegularExpressionValidator1"

runat="server"

ErrorMessage="only characters allowed"

ControlToValidate="TextBox1"

ValidationExpression="^[a-z]*$"></asp:RegularExpressionValidator>

dipa ahuja replied to v k on 18-Aug-11 02:49 AM

Untitled document

function chkValid2() {

var Ename = document.getElementById("Name");

var EnamePatrn = /^[A-Za-z]+$/;

if (!EnamePatrn.test(Ename.value)) {

alert("Enter Characters Only");

return false;

}

else

return true;

}

</script>

<asp:TextBox ID="Name" runat="server"></asp:TextBox>

OR Using Validataor Control

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<%-- RagularExpression Validator --%>

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"

ErrorMessage="Enter Characters Only" Display="Dynamic" ControlToValidate="TextBox1"

ValidationExpression="^[a-zA-Z'.]{1,40}$">Enter Characters Only</asp:RegularExpressionValidator>

Venkat K replied to v k on 18-Aug-11 02:50 AM

Use javascript regular expressions:

function AcceptCharacters()
{
var regexLetter = /[a-zA-z]/;
if(!regexLetter.test(textbox.value)){
alert('Type only character');
return false;
}

Thanks

Reena Jain replied to v k on 18-Aug-11 03:10 AM

Hi,

here is the code for you

private void textBox4_KeyPress(object sender, KeyPressEventArgs e)

{

if

((e.KeyChar
>= 65 && e.KeyChar <= 90) || (e.KeyChar >= 97
&& e.KeyChar <= 122) || e.KeyChar == 32 || e.KeyChar == 8 ||
(e.KeyChar > 47 && e.KeyChar < 58) || (e.KeyChar == 46) ||
(e.KeyChar == 8))

{

e.Handled = false;

}

else

{

e.Handled = true;

}

I would like to give you keycode also for my above code

keychar 65 to 90 is for 'A' to 'Z'
keychar 97 to 122 is for 'a' to 'z'
keychar 8 is for backspace
keychar 47 to 58 is for 0 to 9

but i will suggest if you are using asp.net then you should use client side validation for it, like this

function AllowAlphabet(e)

{

isIE = document.all ? 1 : 0

keyEntry = !isIE ? e.which : event.keyCode;

if (((keyEntry >= '65') && (keyEntry <= '90')) || ((keyEntry >= '97') && (keyEntry <= '122')) || (keyEntry == '46') || (keyEntry == '32') || keyEntry == '45')

return true;

else

{

alert('Please Enter Only Character values.');

return false;

}

<asp:TextBox ID="TextBox1" runat="server" MaxLength="1" onkeypress="return AllowAlphabet(event)"></asp:TextBox>

or
use customer validator, custom validator is just provide u put your own function to validate so u need to write code for validate character only using regular expression in case of using custom validator control
so better is u can use regular expression in Regularexpression validator control this is specific validator control for validate with regular expression

<asp:RegularExpressionValidator id="valRegEx" runat="server"

ControlToValidate="textbox1"

ValidationExpression="[^a-z][A-Z]+$"

ErrorMessage="* entry only character value."

display="dynamic">*

</asp:RegularExpressionValidator>

hope this will help you

v k replied to Reena Jain on 18-Aug-11 03:27 AM

hey thanks
but i want to include space also.. how i can i do this. i.e. space can allowed

Reena Jain replied to v k on 18-Aug-11 03:34 AM

Hi,

here keycode = 32 is for space only, so you can use this javascript function for space also

function AllowAlphabet(e)

{

isIE = document.all ? 1 : 0

keyEntry = !isIE ? e.which : event.keyCode;

if (((keyEntry >= '65') && (keyEntry <= '90')) || ((keyEntry >= '97') && (keyEntry <= '122')) || (keyEntry == '46') || (keyEntry == '32') || keyEntry == '45')

return true;

else

{

alert('Please Enter Only Character values.');

return false;

}

Devil Scorpio replied to v k on 18-Aug-11 10:41 AM

Hi,

You can validate the textbox to accept character only by using javascript

Here is two solution to do so

Solution1:-
<script>
function onkeydown(){
   var ch = String.fromCharCode(event.keyCode);
   var filter = /[a-zA-Z]/   ;
   if(!filter.test(ch)){
      event.returnValue = false;
   }
}
</script>

This can restrict the user to input only characters, but you still have to consider that user can paste numbers, or drag in into textbox.

Solution2:-
Use event.keyCode to accept only char values.
write a function in javascript and call it on onkeypress event of Textbox

function checkNum()
{

if ((event.keyCode > 64 && event.keyCode < 91) || (event.keyCode > 96 && event.keyCode < 123) || event.keyCode == 8)
   return true;
else
   {
     alert("Please enter only char");
     return false;
   }

}