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| -rw-r--r-- | forth.html.markdown | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/forth.html.markdown b/forth.html.markdown index b8b751d9..847895c3 100644 --- a/forth.html.markdown +++ b/forth.html.markdown @@ -55,6 +55,7 @@ Forth, but most of what is written here should work elsewhere. 2 5 swap / \ swap the top with the second element: 5 / 2 6 4 5 rot .s \ rotate the top 3 elements: 4 5 6 4 0 drop 2 / \ remove the top item (dont print to screen): 4 / 2 +1 2 3 nip .s \ remove the second item (similar to drop): 1 3 \ ---------------------- More Advanced Stack Manipulation ---------------------- @@ -151,7 +152,7 @@ create mynumbers 64 , 9001 , 1337 , \ ok (the last `,` is important!) \ ...which is equivalent to: -\ [64, 9001, 1337] +\ Manually writing values to each index: 64 mynumbers 0 cells + ! \ ok 9001 mynumbers 1 cells + ! \ ok 1337 mynumbers 2 cells + ! \ ok @@ -159,12 +160,14 @@ create mynumbers 64 , 9001 , 1337 , \ ok (the last `,` is important!) \ Reading values at certain array indexes: 0 cells mynumbers + ? \ 64 ok 1 cells mynumbers + ? \ 9001 ok -2 cells mynumbers + ? \ 1337 ok -\ Of course, you'll probably want to define your own words to manipulate arrays: -: ?mynumbers ( n -- n ) cells mynumbers + ; \ ok -64 mynumbers 2 cells + ! \ ok -2 ?mynumbers ? \ 64 ok +\ We can simplify it by making a helper word for manipulating arrays: +: arr ( n n -- n ) cells swap + ; +mynumbers 2 arr ? \ 1337 ok + +\ Which we can use for writing too: +20 mynumbers 1 arr ! \ ok +mynumbers 1 arr ? \ 20 ok \ ------------------------------ The Return Stack ------------------------------ |