Question

In C#, the Changed event for a control (say, a numericupdown) gets fired whether the value was change directly by the user or if it was changed programatically as the result of some other event.

Is there a way to determine whether the event occurred as a result of user input? For example, both manually changing the value of numericUpDown1 and clicking on button1 will display ‘value changed’. What if I only wanted to display ‘value changed’ if it was changed through the user clicking on the up/down arrows in the control and not as a result of clicking on button1?

    private void numericUpDown1_ValueChanged(object sender, EventArgs e)     {         MessageBox.Show('value changed');     }      private void button1_Click_1(object sender, EventArgs e)     {         numericUpDown1.Value = 3;     } 

Answer 1

There is no nice way to do it. You can find workarounds for specific cases, e.g.

• listen to MouseDown or something instead of valueChanged on the numeric drop down.

• Set a flag in button click event handler that will prohibit the message box from showing.

  In general you should try to organize your form in a way that it doesn’t matter where the value got changed.