How to fix Character Length in a TextBox

Question

1.00/5 (3 votes)

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Dear fellow,
How can I fix character length in textbox? Say i want to restrict to 3 three characters. It should not only to enter less than or more than three characters. And secondly, I want to allow only text in the textbox. Please help me out.

Posted 18-Jun-10 22:11pm

touseef4pk

Updated 30-Jan-20 17:19pm

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7 solutions

Solution 8

1.To restrict maxlength of textbox with three character, write

<asp:TextBox ID="TextBox1" runat="server" MaxLength="3"></asp:TextBox>

2.To match exactly three character in textbox add following javascript function

JavaScript

function checkLength(obj) {
            if (obj.value.length != 3) {
                alert("Should be exactly three char.");
                obj.focus();
            }
        }

And call the function in onblur event

TextBox1.Attributes.Add("onblur", "checkLength(this)");

3.To allow only text in textbox add following javascript function

JavaScript

function handleKeydown(event) {
            keyEntry = event.keyCode || event.which;
            if (
                ((keyEntry >= '65') && (keyEntry <= '90')) ||
                ((keyEntry >= '97') && (keyEntry <= '122')) ||
                (keyEntry == '46') ||
                (keyEntry == '32') ||
                keyEntry == '45' ||
                keyEntry == '46' ||
                keyEntry == '8' ||
                keyEntry == '35' ||
                keyEntry == '36'||
                keyEntry == '9')
                return true;
            else
                return false;
        }

And add onkeydown & onpaste handler in code behind

TextBox1.Attributes.Add("onkeydown", "return handleKeydown(event)");
TextBox1.Attributes.Add("onpaste", "return handleKeydown(event)");

Hope this will help you.

Posted 30-Jun-10 1:34am

Prosanta Kundu online

Solution 3

For an example on a implenting a validator, see here.

Posted 19-Jun-10 6:43am

Abhinav S

Solution 5

You can add javascript regex validation.

Try "^[a-zA-Z]{3}$" as regular expression for your text box.
This regex will allow only 3 alphabet character.

Posted 21-Jun-10 22:34pm

Ronak Bhavsar

Solution 6

Dear.
Please set maxLength properties of Textbox. if you set this 3 then it will not allow to enter more than three characters.

For allowing only text, use AjaxControlToolkit. you can download from microsoft download.

In ajaxcontrolToolkit, you have to use FilterTextBox. You have to defined the type as 'Integer','Text'.....

check this link

http://www.asp.net/(S(fu2l2uzphr2u3u45q2dnez55))/ajax/AjaxControlToolkit/Samples/[^]

and click on FilteredTextBox

Hope it will help you.

Thanks

Lalit Kumar

Posted 21-Jun-10 23:34pm

Lalit Kumar 5733

Comments

Ankur^\m/ 30-Jun-10 6:52am

Reason for my vote of 2
The OP needs EXACTLY 3 characters.

Solution 7

For 3 Character length use

Maxlength="3"

property in textbox
and for character only i think

AJAX:FilterTextboxExtender

control will work

Posted 30-Jun-10 0:40am

Arun S Rana

Comments

Ankur^\m/ 30-Jun-10 6:51am

Reason for my vote of 1
The OP needs EXACTLY 3 characters. Moreover you have put same answer as above poster(Lalit)

Solution 11

XML

<asp:RegularExpressionValidator ID="RegularExpressionValidator1"
      runat="server" ControlToValidate="txtAgendaDesc"
      ErrorMessage="Please enter maximum 1500 charachters." Text="*" Display="None"
      ValidationExpression="^[a-zA-Z.]{0,1500}$" ValidationGroup="AddAgenda">
</asp:RegularExpressionValidator>

Posted 19-Sep-13 1:57am

Torakami

Updated 30-Jan-20 22:59pm

v2

Comments

Cynetha 23-Jan-15 10:06am

hey, I am new and using telerik tools. I have a radmasked textbox for phone numbers. There is already a maxLength property i have used. I need to make sure the user enters in the minimum numbers. Now do I something similar to the javascripts solutions already provided or is there something else i have to do since its telerik tools.

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Ankur^\m/ · Accepted Answer · 2010-06-18T23:56:00

touseef4pk wrote:
Say i want to restrict to 3 three characters. It should not only to enter less than or more than three characters.

There are many ways:
1) Use Javascript - Write code onblur of the textbox to check if the length is equal to 3 or not.

XML

<asp:TextBox ID="TextBox1" runat="server" onblur="javascript:validate();"></asp:TextBox>

JavaScript

function validate()
    {
        if(document.getElementById("TextBox1").value.length != 3)
        {
            alert("text lenghth must be three");
            document.getElementById("TextBox1").select();
            document.getElementById("TextBox1").focus();
            return false;
        }
        else
        {
            return true;
        }
    }

2) Use RegularExpressionValidator. You need to write a regular expression which checks the value entered is 3 characters.

[Edit]

touseef4pk wrote:
Please tell me how can i write reqular expression to limit characters upto three characters in textbox

Try this: \b[a-zA-Z]{3}\b

[/Edit]

touseef4pk wrote:
I want to allow only text in the textbox.

Text means alphanumeric which is the default for a textbox.
I guess you don't mean that. Please clarify.