Restrict textbox data to int or string

Question

1.00/5 (1 vote)

See more:

C#

string

TextBoxBase

I've a textbox in my forum and I want user to enter only int values

C#

if(textbox1.text==int)
{
\\Calculations
}

else
{
\\Error
}

Posted 11-Apr-13 18:57pm

Zain ul abdeen

Add a Solution

Comments

PrashantSonewane 12-Apr-13 1:05am

Is textbox on ASP .NET page or winform? If on ASP page then use javascript function (with regular expression or reading keycode). In Winform you can check the keycode on textchange event.

Zain ul abdeen 12-Apr-13 1:20am

its a winfrom. How to check the key code?

Sergey Alexandrovich Kryukov 12-Apr-13 1:49am

How WinForm can be in your "forum"?!
—SA

Prasad Khandekar 12-Apr-13 1:40am

You can use MaskedTextBox control.

6 solutions

Solution 1

Hello,

Here is a example directly taken from MSDN. You will have to modify it a bit to suite your needs,

C#

// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
    //If shift key was pressed, it's not a number.
    if (Control.ModifierKeys == Keys.Shift) {
        nonNumberEntered = true;
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

Regards,

Posted 11-Apr-13 19:44pm

Prasad Khandekar

Solution 5

C#

void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!Char.IsDigit(e.KeyChar) && e.KeyCode != Keys.Back )
{
e.Handled = true;
}
}

Posted 12-Apr-13 13:45pm

Clifford Nelson

Solution 3

You can validate that in javascript. Use the following code.

JavaScript

function Validate() {
     var txtValue = document.getElementById("MainContent_txtTestBox").value;
     var checkFlag = isNaN(txtValue);

     if (!checkFlag) {
         return true;
     }
     else {
         alert("Number entered is not an integer");
         return false;
     }
 }

For the textbox, just put the onkeyup event and specify the above function as the handler as shown below.

ASP.NET

<asp:textbox id="txtTestBox" runat="server" onkeyup="Validate()" xmlns:asp="#unknown" />

Using JavaScript instead of server code (code-behind) would reduce the load on the server and improve performance.

Posted 11-Apr-13 21:24pm

Amogh Natu

Solution 4

Dear C# has predefined function to check if the entered character is digit or alphabet on keypress event.

C#

//consider following code to get your problem resolved

Private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (char.IsDigit(e.KeyChar))
{
//your code here
}
if (char.IsLetter(e.KeyChar))
{
//your code here
}
}

I guess it helps you.

Posted 12-Apr-13 8:57am

Raj Parashar

Updated 14-Apr-13 6:21am

v2

Solution 6

Hi,

Use range validation control for numeric values to check it client site.
This will check it client site and save round trip to server.

<asp:RangeValidator
ControlToValidate="tbox1"
MinimumValue="0"
MaximumValue="2147483647"
Type="int"
EnableClientScript="false"
Text="The data must be between 0 and 2147483647!"
runat="server" />

2147483647 is the max value which we can use in ASP.NET

Posted 14-Apr-13 7:37am

Santosh K. Tripathi

Updated 14-Jul-13 18:24pm

v2

Comments

Zain ul abdeen 17-Apr-13 11:45am

Its a desktop software

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Pallavi Waikar · Accepted Answer · 2013-04-11T21:20:00

Solution 2

also try this code..it will accept only int value

C#

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), @"^[0-9\b?]$"))
                e.Handled = true;
        }

Posted 11-Apr-13 21:20pm

Pallavi Waikar

Updated 12-Apr-13 6:45am

v2

Comments

Zain ul abdeen 12-Apr-13 11:24am

Its Working but how to include backspace also

Pallavi Waikar 12-Apr-13 12:45pm

check updated answer

Zain ul abdeen 13-Apr-13 0:14am

Thankyou 1 more thing can you help me out I want to have autocomplete for textbox from database