(Object sender, eventargs e) sender and E

Add a label to your form and double-click the label's mouseclick event. Add the following method: Private void label1_mouseclick (Object sender, mouseeventargs e) {label senderlabel = (Label) sender; // reference the Control Based on sender. Senderlabel. Text = E. Button. tostring (); // Based on the button parameter in E, determine whether it is left or right-click. } Click your label in the form to display the rigle or left mouse button you clicked. Take the button as an example: protected void button#click (Object sender, eventargs e). The sender is the button you click. you can get reference of this button through type conversion: button sendbutton = (button) sender; E is a parameter of the event you click