KeyPressEventArgs Class
Provides data for the KeyPress event.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
| Name | Description | |
|---|---|---|
![]() | KeyPressEventArgs(Char) | Initializes a new instance of the KeyPressEventArgs class. |
| Name | Description | |
|---|---|---|
![]() | Equals(Object^) | Determines whether the specified object is equal to the current object.(Inherited from Object.) |
![]() | Finalize() | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.) |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | MemberwiseClone() | |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
A KeyPressEventArgs specifies the character that is composed when the user presses a key. For example, when the user presses SHIFT + K, the KeyChar property returns an uppercase K.
A KeyPress event occurs when the user presses a key. Two events that are closely related to the KeyPress event are KeyUp and KeyDown. The KeyDown event precedes each KeyPress event when the user presses a key, and a KeyUp event occurs when the user releases a key. When the user holds down a key, duplicate KeyDown and KeyPress events occur each time the character repeats. One KeyUp event is generated upon release.
With each KeyPress event, a KeyPressEventArgs is passed. A KeyEventArgs is passed with each KeyDown and KeyUp event. A KeyEventArgs specifies whether any modifier keys (CTRL, SHIFT, or ALT) were pressed along with another key. (This modifier information can also be obtained through the ModifierKeys property of the Control class.)
Set Handled to true to cancel the KeyPress event. This keeps the control from processing the key press.
Note |
|---|
Some controls will process certain key strokes on KeyDown. For example, RichTextBox processes the Enter key before KeyPress is called. In such cases, you cannot cancel the KeyPress event, and must cancel the key stroke from KeyDown instead. |
For information about the event model, see Handling and Raising Events.
The following example illustrates using the KeyPressEventArgs to count keys as they are pressed and to display the results after each key press. Handled is then set to true to keep the operating system from further processing the key. The example assumes a form with a TextBox placed on it.
public ref class myKeyPressClass { private: static long keyPressCount = 0; static long backspacePressed = 0; static long returnPressed = 0; static long escPressed = 0; TextBox^ textBox1; void myKeyCounter( Object^ sender, KeyPressEventArgs^ ex ) { switch ( ex->KeyChar ) { // Counts the backspaces. case '\b': backspacePressed = backspacePressed + 1; break; // Counts the ENTER keys. case '\r': returnPressed = returnPressed + 1; break; // Counts the ESC keys. case (char)27: escPressed = escPressed + 1; break; // Counts all other keys. default: keyPressCount = keyPressCount + 1; break; } textBox1->Text = String::Concat( backspacePressed, " backspaces pressed\r\n", escPressed, " escapes pressed\r\n", returnPressed, " returns pressed\r\n", keyPressCount, " other keys pressed\r\n" ); ex->Handled = true; } };
You must create a new instance of this class. You must also set the event handler. You can do this in the constructor for your class.
public: myKeyPressClass^ myKeyPressHandler; Form1() { myKeyPressHandler = gcnew myKeyPressClass; InitializeComponent(); textBox1->KeyPress += gcnew KeyPressEventHandler( myKeyPressHandler, &myKeyPressClass::myKeyCounter ); }
When the specified event is raised in the control, the attached method is called and the application can execute code in response to the event.
Available since 1.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.



