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Mention nip, rework Arrays section.

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HorseMD 2014-11-14 11:13:39 +00:00
parent 13a3c11394
commit a49ab049a5
1 changed files with 9 additions and 6 deletions
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15
forth.html.markdown
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@ -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 ------------------------------