about ascii

[youngjeff]

I can't understand the ascii about left arrow, right arrow, up arrow and down arrow .
I just know letter D is 68,what about left arrow?

[Maurits van der Schee]

@youngjeff left arrow is in fact an extended character, mapping to "^[[D" or "27, 91, 68"

    <?php
    exec("stty -icanon"); // turn off input buffering
    while (true) echo " ".ord(fgetc(STDIN)).",";

You can try the above PHP script on the command line and see it for yourself.