OpenEuphoria

2. Re: newbie questions

• Posted by DerekParnell (admin) Jul 01, 2013
• 1217 views

Yes get_key() does respond to ESC, but you might actually want to use another function. The get_key() function returns immediately. It either returns -1 (to indicate that there was no key press waiting to be responded to yet) or the code for the current key press. Typically, one uses this function in a loop, so your application can do stuff while there is no key presses waiting to process. You might want to use wait_key() instead. That function waits for the user to press a key, if a key a not already been pressed.

integer keycode 
 
while 1 do 
    keycode = get_key() 
    while keycode != -1 do 
        -- I've got a keystroke to use. 
        process_code(keycode) 
        keycode = get_key() 
    end while 
    -- Do something while waiting for the next keystroke. 
    whatever() 
end while 
 

There is a difference between an EMPTY sequence and an UNASSIGNED sequence. When a variable is declared, and if there is no initial assignment on the declaration statement, the variable has NO VALUE. It is unassigned. A sequence is not assigned by default to 'empty' when it is declared, but it is in a state called 'unassigned'.

sequence S_One 
sequence S_Two = {} 
sequence S_Three = {1,2,3} 
 
? S_Three --> {1,2,3} 
? S_Two   --> {} 
? S_One   --> ** CRASH Sequence has not been assigned anything yet.