In a TextBox I'm monitoring the text changes. I need to check the text before doing some stuff. But I can only check the old text in the moment. How can I get the new Text ?
private void textChanged(object sender, EventArgs e)
{
// need to check the new text
}
I know .NET Framework 4.5 has the new TextChangedEventArgs
class but I have to use .NET Framework 2.0.
The TextChanged event is raised when the content of the text box changes between posts to the server. The event is only raised if the text is changed by the user; the event is not raised if the text is changed programmatically.
The event handler is called whenever the contents of the TextBox control are changed, either by a user or programmatically. This event fires when the TextBox control is created and initially populated with text.
To see all changes to the text in a TextBox, you can handle the TextChanged event. This event fires after the text has changed. In the TextChanged event, the easiest way to inspect the text being entered is to just look at the value of the Text property.
Getting the NEW value
You can just use the Text
property of the TextBox
. If this event is used for multiple text boxes then you will want to use the sender
parameter to get the correct TextBox
control, like so...
private void textChanged(object sender, EventArgs e)
{
TextBox textBox = sender as TextBox;
if(textBox != null)
{
string theText = textBox.Text;
}
}
Getting the OLD value
For those looking to get the old value, you will need to keep track of that yourself. I would suggest a simple variable that starts out as empty, and changes at the end of each event:
string oldValue = "";
private void textChanged(object sender, EventArgs e)
{
TextBox textBox = sender as TextBox;
if(textBox != null)
{
string theText = textBox.Text;
// Do something with OLD value here.
// Finally, update the old value ready for next time.
oldValue = theText;
}
}
You could create your own TextBox control that inherits from the built-in one, and adds this additional functionality, if you plan to use this a lot.
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