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| author | Boris Verkhovskiy <boris.verk@gmail.com> | 2024-04-03 02:30:27 -0700 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-04-03 02:30:27 -0700 |
| commit | 6d87022050ffbd5d818781427329c5362e3df197 (patch) | |
| tree | 3809b2b1a7790d8b30e6d694c575eb68f02f661c /forth.html.markdown | |
| parent | c76b8f690a577d9ff89947d79c36a96a7c3b4deb (diff) | |
| parent | e8dabf3c1955e1a458e8bc936587ad59772a9c33 (diff) | |
Merge branch 'master' into patch-1
Diffstat (limited to 'forth.html.markdown')
| -rw-r--r-- | forth.html.markdown | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/forth.html.markdown b/forth.html.markdown index ff094017..4e2f7599 100644 --- a/forth.html.markdown +++ b/forth.html.markdown @@ -93,8 +93,8 @@ see square \ : square dup * ; ok \ ------------------------------------ Loops ----------------------------------- -\ `do` is also a compile-only word. -: myloop ( -- ) 5 0 do cr ." Hello!" loop ; \ ok +\ `?do` is also a compile-only word. +: myloop ( -- ) 5 0 ?do cr ." Hello!" loop ; \ ok myloop \ Hello! \ Hello! @@ -102,16 +102,17 @@ myloop \ Hello! \ Hello! ok -\ `do` expects two numbers on the stack: the end number and the start number. +\ `?do` expects two numbers on the stack: the end number (exclusive) and the +\ start number (inclusive). \ We can get the value of the index as we loop with `i`: : one-to-12 ( -- ) 12 0 do i . loop ; \ ok -one-to-12 \ 0 1 2 3 4 5 6 7 8 9 10 11 12 ok +one-to-12 \ 0 1 2 3 4 5 6 7 8 9 10 11 ok -\ `?do` works similarly, except it will skip the loop if the end and start -\ numbers are equal. -: squares ( n -- ) 0 ?do i square . loop ; \ ok -10 squares \ 0 1 4 9 16 25 36 49 64 81 ok +\ `do` works similarly, except if start and end are exactly the same it will +\ loop forever (until arithmetic underflow). +: loop-forever 1 1 do i square . loop ; \ ok +loop-forever \ 1 4 9 16 25 36 49 64 81 100 ... \ Change the "step" with `+loop`: : threes ( n n -- ) ?do i . 3 +loop ; \ ok |