key (event)

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Grid Modem.png  Event key
Fired when any key (except Escape) is pressed while the terminal is focused. You can compare the values it gives you to the constants in the keys API (eg, keys.up, keys.down, etc).

If the button pressed represented a printable character, then the "key" event will be followed immediately by a "char" event - you're generally better off pulling that if you're wanting text input (as "key" events don't indicate eg the case of what was typed, whereas "char" events do). When the button is released, a "key_up" event may be fired as well (assuming ComputerCraft 1.74 or later).
Returned Object 1 The numerical key value of the key pressed
Returned Object 2 A boolean indicating whether the key event was generated while holding the key (true), rather than pressing it the first time (false).


Grid paper.png  Example
Print each key pressed on the keyboard whenever a "key" event is fired. Use Ctrl+T (Windows) to terminate the loop.
Code
while true do
  local event, key, isHeld = os.pullEvent("key")
  
  write( keys.getName( key ) )
  print( isHeld and " is being held." or " was pressed." )
end
Output Any key that is pressed.



Grid paper.png  Example
Moves a white square around the screen in response to the arrow keys. Press q to quit.
Code
local x, y = 1, 1

local xSize, ySize = term.getSize()

while true do
	-- Draw a white space at the current x/y co-ord:
	term.setBackgroundColor(colours.black)
	term.clear()
	term.setCursorPos(x, y)
	term.setBackgroundColor(colours.white)
	term.write(" ")
	
	-- Wait for a key event:
	local event, key = os.pullEvent("key")
	
	-- Act on it:
	if key == keys.up and y > 1 then
		y = y - 1
	elseif key == keys.down and y < ySize then
		y = y + 1
	elseif key == keys.left and x > 1 then
		x = x - 1
	elseif key == keys.right and x < xSize then
		x = x + 1
	elseif key == keys.q then
		break
	end
end



Key scan codes

These scan codes are also available as constants in the keys API, and can be translated from numerical codes to strings using keys.getName.

Click for a larger copy of this image - contains keys and their event numbers.