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Question
Sunday, September 1, 2013 3:39 AM | 1 vote
hi friends,
is there away to make a textbox accept only numeric, del key and backspace key?
I used the following code but it doesn't work:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if ( char.IsDigit(e.KeyChar) == true || e.KeyChar == Convert.ToChar(Keys.Back) || e.KeyChar == Convert.ToChar(Keys.Delete) )
{
e.Handled = true;
}
}
thanks
I use Visual studio 2010 professional and SQL server 2008 developer edition!
All replies (12)
Sunday, September 1, 2013 4:22 AM ✅Answered
numeric check keypress event
http://msdn.microsoft.com/en-us/library/ms171538.aspx
ASCII Key codes
http://help.adobe.com/en_US/AS2LCR/Flash_10.0/help.html?content=00000520.html
Sunday, September 1, 2013 4:31 AM ✅Answered
public partial class Form1 : Form
{
/// <summary>
/// Whether Del is pressed or not
/// </summary>
private bool isDelPressed = false;
public Form1()
{
InitializeComponent();
}
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
int n = (int)e.KeyChar;
e.Handled = !(n == 8 || (n >= 48 && n <= 57) || isDelPressed);
}
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
isDelPressed = (e.KeyCode == Keys.Delete);
}
}
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Sunday, September 1, 2013 5:36 AM
I always prefer to do it via client side Javascript... It is faster than using code behind
<asp:TextBox ID="txtNumber" runat="server" onkeypress="AllowNumeric();" MaxLength="8"></asp:TextBox>
Choose the Javascript you prefer.
function isNumber(n) { return !isNaN(parseFloat(n)) && isFinite(n);}function AllowNumeric() { if ((event.keyCode > 47 && event.keyCode < 58) || (event.keyCode == 46) || (event.keyCode == 45)) { event.returnValue = true; } else { event.returnValue = false; }}
Sunday, September 1, 2013 5:37 AM
Maybe the problem of Windows Form instead of Web Form;)
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Sunday, September 1, 2013 5:52 AM
True, the OP doesn't specify whether it is for a Windows Form or a Web Form... I made the assumed Web Form because he said his code behind example didn't work and with a Web Form using code behind for that would be tricky...
BTW here is a really ugly Javascript AllowNumeric I created a long time ago and haven't had time since to make it nice. A lot of nested if's
function allowNumeric(textElement, AllowNegNum, LeftDigits, RightDigits) { var caretPos = getCursorPos(textElement); var numValue = textElement.value; var decimalPos = numValue.indexOf('.'); var negPresent = numValue.indexOf('-'); if (AllowNegNum != true) AllowNegNum = false; if (AllowNegNum) { //Allows negative numbers. if ((event.keyCode > 47 && event.keyCode < 58) || (event.keyCode == 46) || (event.keyCode == 45)) { //Allow minus sign only in first position if ((caretPos == 0) && (event.keyCode == 45)) { event.returnValue = true; } else if ((caretPos == 0) && (event.keyCode != 45)) { event.returnValue = true; } else if ((caretPos != 0) && (event.keyCode != 45)) { event.returnValue = true; } else { event.returnValue = false; } //One decimal point allowed if ((event.keyCode) == 46 && (decimalPos > -1)) { event.returnValue = false; } } else { event.returnValue = false; } } else { //Disallows negative numbers. if ((event.keyCode > 47 && event.keyCode < 58) || (event.keyCode == 46)) { event.returnValue = true; } else { event.returnValue = false; } //One decimal point allowed if ((event.keyCode) == 46 && (decimalPos > -1)) { event.returnValue = false; } } addValue = 0; if (negPresent > -1) { addValue = 1; } if (event.keyCode > 47 && event.keyCode < 58) { //alert('in decimal check'); var decimalSplit = numValue.split('.'); if (decimalSplit[0].length < (LeftDigits + addValue)) { event.returnValue = true; } else { event.returnValue = false; } if (decimalSplit.length == 2) { if (decimalSplit[1].length < RightDigits) { event.returnValue = true; } else { event.returnValue = false; } if (decimalSplit[0].length < (LeftDigits + addValue) && (decimalSplit[1].length == RightDigits)) { if (caretPos <= decimalPos) { event.returnValue = true; } else { event.returnValue = false; } } } }}
Sunday, September 1, 2013 6:22 AM
Paul;)
Hahaha……TextBox in the WebForm doesn't have such events like Key_Press.....
Sniff_bits;)
Please confirm
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Tuesday, September 3, 2013 1:46 AM
On the contrary my friend. I actually have a few working web applications that does use keypress and it works just fine. The following is one of the more elabarate uses in a textbox I have
<asp:TextBox ID="control_Hours" runat="server" Width="50px" onkeypress="APPJS.allowNumeric(this, false, 2, 2);" onkeyup="APPJS.checkLimit(this, '24');" onblur="APPJS.setMaskUnderScoreZero();"></asp:TextBox>
The class and inheritance of the page
public partial class PageName : System.Web.UI.Page{.................}
Tuesday, September 3, 2013 2:00 AM
It doesn't show in the intellisence... I actually have a working web application that does us key_press and it works just fine.
Hi again;)
Do you mean TextBox control of Web has Key_Pressed event at server-side or client side?
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Tuesday, September 3, 2013 2:29 AM
ProgrammingVolunteer ... I like that name BTW
I actually edited the post you quoted to clarify... And actually my intellisense shows it; so the part "It doesn't show in the intellisence..." was incorrect on my part.
It is all happening on the client side regarding the code I posted... There probably is a code behind way to do it even if you need to define the event handler your self... but alas I haven't needed to do that in the scenerios I've done this.
Tuesday, September 3, 2013 2:44 AM
Hahah……
Nothing special but just I wonder since the user is using Server side……
Waiting for user to response us;)
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Tuesday, September 3, 2013 3:20 AM
This is THE WRONG FORUM for webforms. Cant you people read? This is a .net forum.
Renee
"MODERN PROGRAMMING is deficient in elementary ways BECAUSE of problems INTRODUCED by MODERN PROGRAMMING." Me
Monday, October 19, 2015 2:43 PM
You did the mistake which is reverse of your need. You need to accept only numbers or delete or backspace but prevented when these keys will press. e.Handle = true which prevents the input.
Make your code like this.
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if ( !char.IsDigit(e.KeyChar) || e.KeyChar != Convert.ToChar(Keys.Back) || e.KeyChar != Convert.ToChar(Keys.Delete) )
{
e.Handled = true;
}
}Orprivate void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if ( !char.IsDigit(e.KeyChar) || e.KeyChar != Convert.ToChar(Keys.Back) || e.KeyChar != Convert.ToChar(Keys.Delete) )
{
e.Handled = false;
}
}