Develop Reference

Uppercase data enter at application level

One of our clients wants all entered data to be uppercased. I don't want to do it textbox by textbox, etc.
Are the any way to do it at application level?

Solution 1: if you want to read UserInput in UpperCase you can use ToUpper() method.
Try This:
String str=textBox1.Text.ToUpper();
Solution 2:
if you want to Displayand read the UserInput in UpperCase, you can handle the TextChanged event of the TextBox as below:
private void textBox1_TextChanged(object sender, EventArgs e)
{
textBox1.Text = textBox1.Text.ToUpper();
textBox1.Select(textBox1.Text.Length, 0);
}

You can write the KeyPress event once.
private void txtBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar >= 'a' && e.KeyChar <= 'z')
e.KeyChar -= (char)32;
}
32 is just the difference in ASCII values between lowercase and uppercase letters.

You can subclass the TextBox control, create a derived class that only works with uppercase, and use your derived class instead of the original TextBox.
This is a possible way to implement it:
using System;
namespace UpperCaseTextBox
{
public class UpperCaseTextBox : System.Windows.Forms.TextBox
{
protected override void OnTextChanged(EventArgs e)
{
var selectionStart = this.SelectionStart;
var selectionLength = this.SelectionLength;
this.Text = this.Text.ToUpper();
this.SelectionStart = selectionStart;
this.SelectionLength = selectionLength;
base.OnTextChanged(e);
}
}
}
The above code has been tested, although it is just for demostration.
Note 1: I recommend to do this in a separated dll project, it will be easier to use (you have to compile build the control before placing it in the forms designer) and maintain. If you decide to create the dll, remember that you need to add a reference in the dll to System.Windows.Forms and also that you need a reference to your dll in your winforms application to use it.
Note 2: You may be interested in creating a variant of this by adding a new property to set the TextBox to normal, uppercase only or lowercase only. You may also want to create a mechanism to control this property for all the instances in your AppDomain (hint: that can be a static field). Why? Because you don't know what else will the client ask for next.

C# When using a KeyPress event on a text box, why cant i enter a minus sign?

Im using VS2010, and I have a text box... I assign a KeyPress on the box, abd set the method like so:
private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = true;
}
I noticed that i am no longer able to enter any special keys such as the minus (-) and plus (+) sign into the textbox. Can someone please explain to me why i am no longer able to do this, and what i can do to fix this?
Ultimately I'm trying to only allow numeric keys to be entered, and i also want to allow the (-) minus sign, but if i cant get the minus sign in there, then i guess i wont be able to limit the text of the box

This should finish the job for you.
private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar >= '0' && e.KeyChar <= '9') return;
if (e.KeyChar == '+' || e.KeyChar == '-') return;
e.Handled = true;
}
Here is how it works. If the character typed is one that you want, simply return from the function and let the normal handler take care of it. All other characters are marked as handled and so processing on them stops. Since nothing is done with them they are essentially thrown away. You could put everything in one if statement but I left it this way for clarity

I changed your code a little and added logic that only accepts 1, 2 or +, which was one of your problem characters. Hope this helps you!
private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = true;
if (e.KeyChar == '1' || e.KeyChar == '2' || e.KeyChar == '+') textBox1.AppendText(e.KeyChar.ToString());
}

Actually, you should do like so:
private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == '1' || e.KeyChar == '2' || e.KeyChar == '+')
e.Handled = false;
else
e.Handled = true;
}
Of course, you'll want to replace the individual tests by a method that will return whether or not the key is allowed.
Cheers

As it is now, your code won't allow anything to be entered. The e.Handled statement cancels the key stroke. The code below will allow any numeric character, and the minus sign. If you only want the minus sign in the first position in the textbox you will have to test the TextLength property before allowing the character.
private void MyButton_KeyPress(object sender, KeyPressEventArgs e
{
int i = 0;
if (!int.TryParse(e.KeyChar.ToString(), out i))
{
if (e.KeyChar.CompareTo('-')!=0)
{
e.Handled = true;
}
}
}

Restrict numbers and letters in textbox - C#

I want to restrict what numbers and letters can be entered into a textbox. Let's say I only want to allow numbers 0-5 and letters a-d (both lower and uppercase).
I already tried using a masked text box but it only let me specify numbers only, letters only (both without restriction) or numbers and letters together but in a particular order.
Best scenario would be: user tries to enter number 6 and nothing gets entered into the textbox, same for letters outside the range a-f.
I think the best event to use would be the Keypress event, but I am at a loss as to how I can achieve the restriction thing.

Use the KeyPress Event for your textbox.
protected void myTextBox_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs)
{
e.Handled = !IsValidCharacter(e.KeyChar);
}
private bool IsValidCharacter(char c)
{
bool isValid = true;
// put your logic here to define which characters are valid
return isValid;
}

// 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;
}
}

Override the PreviewKeyDownEvent like this:
private void textBox1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
if (e.KeyCode == Keys.A || e.KeyCode == Keys.B || ...)
e.IsInputKey = true;
else
e.IsInputKey = false;
}
This will tell the textBox which keys it will consider as a user input or not.

Use the KeyDown event and if the e.Key is not in your allowable set, then just e.Handled = true.
An alternative would be accept all input, validate it and then provide useful feedback to the user, for example an error label asking them to enter data within a certain range. I prefer this method as the user knows something went wrong and can fix it. It is used throughout the web on web forms and would be not at all surprising for a user of your app. Pressing a key and getting no response at all might be confusing!
http://en.wikipedia.org/wiki/Principle_of_least_astonishment

The Keypress event is probably your best bet. Do a check there if the entered char is not the char you want, set e.SuppressKey to true to make sure the KeyPress event is not fired, and the char is not added to the textbox.

If you are using ASP.NET Web Forms a regular expression validation would be the easiest. In MVC, a jQuery library such as MaskedEdit would be a good place to start. The answers above document the Windows forms approach well.

Restrict Characters Allowed In TextBox(Entering Money Amount)

So I have a Subtotal TextBox where an amount like $546.75 can be entered. Now, I want to make sure that only numbers, ONE decimal, One Dollar Symbol and commas allowed only every 3 places (100,000,000). Is this possible? Maybe not the commas, but at least the numbers, decimal, and dollar symbol.

Why you dont put the money sign "$" out side of the textBox (create a label just infrontof textBox), then you will not have to worry about this character, but only about numbers. And it looks better (in my opinion).
Then you can use this code:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != (Char)Keys.Back) //allow backspace (to delete)
{
e.Handled = !char.IsNumber(e.KeyChar);
}
}

All validation should be performed manually on KeyPress event.
Here described validation for numeric values values. You will need to check the '$' sign and decimals additionally.

I think you are using WinForms and not WPF. If that is the case then you could use System.Windows.Forms.ErrorProvider (you can drag-drop one from toolbox to your form) along with regular expressions to do the validation.
WARNING: The regex pattern string below may not do exactly you want but hopefully conveys the idea.
Some match examples... "$4,000.00", "-$4000.00", "-$400.00"
private void textBox1_Validating(object sender, CancelEventArgs e)
{
string error = null;
string pattern = #"^\$?\-?([1-9]{1}[0-9]{0,2}(\,\d{3})*(\.\d{0,2})?|[1-9]{1}\d{0,}(\.\d{0,2})?|0(\.\d{0,2})?|(\.\d{1,2}))$|^\-?\$?([1-9]{1}\d{0,2}(\,\d{3})*(\.\d{0,2})?|[1-9]{1}\d{0,}(\.\d{0,2})?|0(\.\d{0,2})?|(\.\d{1,2}))$|^\(\$?([1-9]{1}\d{0,2}(\,\d{3})*(\.\d{0,2})?|[1-9]{1}\d{0,}(\.\d{0,2})?|0(\.\d{0,2})?|(\.\d{1,2}))\)$";
if (!Regex.IsMatch(textBox1.Text, pattern))
{
error = "Please enter a US currency value.";
e.Cancel = true;
}
errorProvider1.SetError((Control)sender, error);
}

There are a number of articles on numeric textboxes
Numeric TextBox
http://www.daniweb.com/software-development/csharp/threads/95153
http://www.codeproject.com/KB/vb/NumericTextBox.aspx
I use this one in my projects
http://www.codeproject.com/KB/edit/ValidatingTextBoxControls.aspx

//tb - is the name of text box
private void tb_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
char[] inputChar = e.Text.ToCharArray();
if (char.IsNumber(inputChar[0]))
{
e.Handled = false;
}
else
{
e.Handled = true;
}
// another method.
if (char.IsDigit(inputChar[0]))
{
e.Handled = false;
}
else
{
e.Handled = true;
}
}

Have you tried Ajax Controls?
http://www.aspsnippets.com/Articles/ASPNet-AJAX-FilteredTextBoxExtender-Control-Example.aspx
Simples. :)

Allow only alphanumeric in textbox

I have a textbox that should disallow entering any special characters.
The user can enter :
A-Z
a-z
0-9
Space
How can I make the KeyDown event to do this?

Handling the KeyDown or KeyPress events is one way to do this, but programmers usually forget that a user can still copy-and-paste invalid text into the textbox.
A somewhat better way is to handle the TextChanged event, and strip out any offending characters there. This is a bit more complicated, as you have to keep track of the caret position and re-set it to the appropriate spot after changing the box's Text property.
Depending on your application's needs, I would just let the user type in whatever they want, and then flag the textbox (turn the text red or something) when the user tries to submit.

Just wanted to add some code for those ending up here by search:
private void Filter_TextChanged(object sender, EventArgs e)
{
var textboxSender = (TextBox)sender;
var cursorPosition = textboxSender.SelectionStart;
textboxSender.Text = Regex.Replace(textboxSender.Text, "[^0-9a-zA-Z ]", "");
textboxSender.SelectionStart = cursorPosition;
}
This is a change filter, so handles copy and paste, and preserves cursor position so that changing text in the middle works properly.
Note it uses the 'sender' to get the control name, allowing this one function to be linked to multiple textbox boxes, assuming they need the same filter. You can link multiple controls by going to the event section of a control and manually picking the function for the TextChanged event.

Use a regex to filter out the other characters. Or use Char.IsDigit, IsXXX methods to filter out unwanted characters. Lots of ways to do this.
Update: If you must use KeyDown then it seems that you need to also handle KeyPressed and set obEventArgs.Handled = true to disallow the characters. See the example on the KeyDown MSDN Page
Update: Now that you specify it's WPF. The below code will allow only a-z and A-Z characters to be entered into the textbox. Extend as needed...
private void _txtPath_KeyDown(object sender, KeyEventArgs e)
{
if ((e.Key < Key.A) || (e.Key > Key.Z))
e.Handled = true;
}
This will break if you copy-paste stuff into the text-box. Validate the entire text once the user leaves the control or when he clicks OK/Submit as MusicGenesis says.

private void _txtPath_KeyDown(object sender, KeyEventArgs e)
{
if ((e.Key < Key.A) || (e.Key > Key.Z))
e.Handled = true;
}

I think it's worth considering doing the filtering on the TextBox's TextChanged event. You can create an operation that gets rid of any non-valid characters from your text string. This is a bit more messy than blocking the KeyDown event.
But, I think this is the way to go because you are not blocking WPF's built-in KeyDown/Up event handling mechanisms, so copy/paste still works. You would be working at a higher level of abstractions so I think it will be easier to figure out what is going on.

I ran into this in silverlight and wrote something like this.
private string _filterRegexPattern = "[^a-zA-Z0-9]"; // This would be "[^a-z0-9 ]" for this question.
private int _stringMaxLength = 24;
private void _inputTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
if (!string.IsNullOrEmpty(_filterRegexPattern))
{
var text = _inputTextBox.Text;
var newText = Regex.Replace(_inputTextBox.Text, _filterRegexPattern, "");
if (newText.Length > _stringMaxLength)
{
newText = newText.Substring(0, _stringMaxLength);
}
if (text.Length != newText.Length)
{
var selectionStart = _inputTextBox.SelectionStart - (text.Length - newText.Length);
_inputTextBox.Text = newText;
_inputTextBox.SelectionStart = selectionStart;
}
}
}

I accomplish this with a custom Dependency Property. It's reusable for any TextBox control, is much faster and more efficient to use than building key events, and makes my code files much cleaner.
In addition, it can handle other input methods which does not trigger key events, such as pasting a value into the TextBox using the mouse.
The code for the custom DP looks like this:
// When set to a Regex, the TextBox will only accept characters that match the RegEx
/// <summary>
/// Lets you enter a RegexPattern of what characters are allowed as input in a TextBox
/// </summary>
public static readonly DependencyProperty AllowedCharactersRegexProperty =
DependencyProperty.RegisterAttached("AllowedCharactersRegex",
typeof(string), typeof(TextBoxProperties),
new UIPropertyMetadata(null, AllowedCharactersRegexChanged));
// Get
public static string GetAllowedCharactersRegex(DependencyObject obj)
{
return (string)obj.GetValue(AllowedCharactersRegexProperty);
}
// Set
public static void SetAllowedCharactersRegex(DependencyObject obj, string value)
{
obj.SetValue(AllowedCharactersRegexProperty, value);
}
// Events
public static void AllowedCharactersRegexChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
var tb = obj as TextBox;
if (tb != null)
{
if (e.NewValue != null)
{
tb.PreviewTextInput += Textbox_PreviewTextChanged;
DataObject.AddPastingHandler(tb, TextBox_OnPaste);
}
else
{
tb.PreviewTextInput -= Textbox_PreviewTextChanged;
DataObject.RemovePastingHandler(tb, TextBox_OnPaste);
}
}
}
public static void TextBox_OnPaste(object sender, DataObjectPastingEventArgs e)
{
var tb = sender as TextBox;
bool isText = e.SourceDataObject.GetDataPresent(DataFormats.Text, true);
if (!isText) return;
var newText = e.SourceDataObject.GetData(DataFormats.Text) as string;
string re = GetAllowedCharactersRegex(tb);
re = string.Format("[^{0}]", re);
if (Regex.IsMatch(newText.Trim(), re, RegexOptions.IgnoreCase))
{
e.CancelCommand();
}
}
public static void Textbox_PreviewTextChanged(object sender, TextCompositionEventArgs e)
{
var tb = sender as TextBox;
if (tb != null)
{
string re = GetAllowedCharactersRegex(tb);
re = string.Format("[^{0}]", re);
if (Regex.IsMatch(e.Text, re, RegexOptions.IgnoreCase))
{
e.Handled = true;
}
}
}
And it's used like this:
<TextBox Text="{Binding SomeValue, UpdateSourceTrigger=PropertyChanged}"
local:TextBoxHelpers.AllowedCharactersRegex="a-zA-Z0-9\s" />

I know that winForms have available a MaskedTextBox control, which lets you specify exactly this sort of thing. I don't know WPF, so I dunno if that's available there, but if it is, do that. Its MUCH easier than all this stuff with keypresses and events, and more robust too.

The easiest way to do this would be to included the Extended WPF Toolkit which has a control for doing exactly what you are asking for by specifying a mask.
http://wpftoolkit.codeplex.com/wikipage?title=MaskedTextBox&referringTitle=Home
It will also display the mask in the text box as you are inputting if required.
(It also has many other useful controls)

and your regExp could look like [0-9a-zA-Z]* to allow only English alphanumeric chracters

only alphanumeric TextBox WPF C#,
sorry for my english.. but with this code for WPF, c#, I only permit alphanumeric
private void txtTraslado_TextChanged(object sender, KeyEventArgs e)
{
if (((e.Key < Key.NumPad0)||(e.Key > Key.NumPad9))&&((e.Key < Key.A)||(e.Key > Key.Z)))
{
e.Handled = true;
}
}

Use Asp.NET AJAX Control Toolkit
<%# Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>
And Use FilteredTextBoxExtender
<asp:TextBox ID="txt_gpf_no" runat="server" CssClass="textbox"
MaxLength="10"></asp:TextBox>
<asp:FilteredTextBoxExtender ID="FilteredTextBoxExtender_gpf_no" runat="server" Enabled="True"
TargetControlID="txt_gpf_no" FilterType="UppercaseLetters,LowercaseLetters,Custom" ValidChars="1234567890 ">
</asp:FilteredTextBoxExtender>

in my.Net Framework 4.5 C# application
private void txtRF_Register_Val_KeyDown(object sender, KeyEventArgs e)
{
//only enable alphanumeric
if (!(((e.KeyCode < Keys.NumPad0) || (e.KeyCode > Keys.NumPad9)) && ((e.KeyCode < Keys.A) || (e.KeyCode > Keys.E))))
{
e.SuppressKeyPress = false;
}
else
{
e.SuppressKeyPress = true;
}
}