Using bitwise logic to test Control.MouseButtons

Question

Can someone kindly explain how this works?

if ((Control.MouseButtons & MouseButtons.Left) != 0)

MSDN only says that Control.MouseButtons Property gets a value indicating which of the mouse buttons is in a pressed state but I can't understand how that '&' works and why should it be different than 0.

score 2 · Accepted Answer · answered Aug 27 '13 at 15:49

The MouseButtons property is a bit flag vs. a normal enum. That means it can simultaneously hold values like MouseButtons.Left and MouseButtons.Right. It does this by using the 1 / 0 states of specific bits within the value to represent states. MouseButtons.Left and MouseButtons.Right represent such states.

The & operation is known as bitwise and. It will return a value which has the bits which were 1 in both the left and the right value. Hence this particular expression will only be non-zero when the MouseButtons.Left bit is set in MouseButtons meaning that the left button is indeed pressed

ECXELLENT! Thank you so much sir – Aaron Ullal Aug 27 '13 at 16:09 — Aaron Ullal, Aug 27 '13 at 16:09

score 1 · Answer 2 · answered Aug 27 '13 at 15:48

1

Control.MouseButtons is a bitwise combination.

The expression:

if ((Control.MouseButtons & MouseButtons.Left) != 0)

is checking if the bit MouseButtons.Left is set (has value 1).

answered Aug 27 '13 at 15:48

Alberto

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Using bitwise logic to test Control.MouseButtons

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