Martin Kalbfuß wrote:

I have another problem with my text snake game. It's about the use of the keyboard functions of Crt.

The player record has some fields holding the keys for changing the direction of the snake.

I want the following key sets as standard.

player 1:

left -> a right -> d up -> w down -> s

player 2:

left -> arrow left right -> arrow right up -> arrow up down -> arrow down

I found the scancodes for the arrow keys on the net, and they are working. But the scancodes I found for the letters doesn't. I also read that usb keyboards have different scancodes.

Is it possible to use scancodes platform independent?

The CRT unit tries to be as BP compatible as possible, so it does the same as BP does: For normal keys it returns the ASCII code, for function keys it returns Chr (0) followed by the scan code.

On non-Dos platforms, it maps the keys to the Dos scancodes, so they're quite platform independent.

BTW, the scan codes are defined in crt.inc (which is automatically included in the CRT unit), e.g. ksLeft for the left key. (Note that not all keys and combinations may be available on all platforms, but the common keys such as left/right/up/down should be available on any non-stoneage keyboard. ;-)

BTW^2, since the Chr (0) / scancode sequence is often a bit clumsy to handle (you cannot just ignore the Chr (0), as many scancodes overlap with regular ASCII characters), GPC's CRT unit provides as an extension the function ReadKeyWord which returns an integer: for normal keys the ordinal value of the ASCII code (0 .. 255), for function keys 256 times the scancode. These codes are also defined in crt.inc, e.g. kbLeft.

Frank