| @node Notation, Arithmetic, Words, Words |
@node Notation, Arithmetic, Words, Words |
| @section Notation |
@section Notation |
| |
|
| The Forth words are describes in this section in the glossary notation |
The Forth words are described in this section in the glossary notation |
| that has become a de-facto standard for Forth texts, i.e. |
that has become a de-facto standard for Forth texts, i.e. |
| |
|
| @quotation |
@quotation |
| additional difficulty, you don't know how many cells a floating point |
additional difficulty, you don't know how many cells a floating point |
| numkber takes. It is reportedly possible to write words in a way that |
numkber takes. It is reportedly possible to write words in a way that |
| they work also for a unified stack model, but we do not recommend trying |
they work also for a unified stack model, but we do not recommend trying |
| it. Also, a Forth system to keep the local variables on the return |
it. Also, a Forth system is allowed to keep the local variables on the |
| stack. This is reasonable, as local variables usually eliminate the need |
return stack. This is reasonable, as local variables usually eliminate |
| to use the return stack explicitely. So, if you want to produce a |
the need to use the return stack explicitely. So, if you want to produce |
| standard complying program and if you are using local variables in a |
a standard complying program and if you are using local variables in a |
| word, forget about return stack manipulations in that word (see the |
word, forget about return stack manipulations in that word (see the |
| standard document for the exact rules). |
standard document for the exact rules). |
| |
|
| @var{code} |
@var{code} |
| ENDIF |
ENDIF |
| @end example |
@end example |
| |
or |
| @example |
@example |
| @var{flag} |
@var{flag} |
| IF |
IF |
| between @var{limit-1} and @var{limit} is crossed. E.g.: |
between @var{limit-1} and @var{limit} is crossed. E.g.: |
| |
|
| 4 0 ?DO i . 2 +LOOP prints 0 2 |
4 0 ?DO i . 2 +LOOP prints 0 2 |
| |
|
| 4 1 ?DO i . 2 +LOOP prints 1 3 |
4 1 ?DO i . 2 +LOOP prints 1 3 |
| |
|
| The behaviour of @code{@var{n} +LOOP} is peculiar when @var{n} is negative: |
The behaviour of @code{@var{n} +LOOP} is peculiar when @var{n} is negative: |
| |
|
| -1 0 ?DO i . -1 +LOOP prints 0 -1 |
-1 0 ?DO i . -1 +LOOP prints 0 -1 |
| |
|
| 0 0 ?DO i . -1 +LOOP prints nothing |
0 0 ?DO i . -1 +LOOP prints nothing |
| |
|
| Therefore we recommend avoiding using @code{@var{n} +LOOP} with negative |
Therefore we recommend avoiding using @code{@var{n} +LOOP} with negative |
| case behaves symmetrical to the positive case: |
case behaves symmetrical to the positive case: |
| |
|
| -2 0 ?DO i . -1 +LOOP prints 0 -1 |
-2 0 ?DO i . -1 +LOOP prints 0 -1 |
| |
|
| -1 0 ?DO i . -1 +LOOP prints 0 |
-1 0 ?DO i . -1 +LOOP prints 0 |
| |
|
| 0 0 ?DO i . -1 +LOOP prints nothing |
0 0 ?DO i . -1 +LOOP prints nothing |
| |
|
| The loop is terminated when the border between @var{limit-sgn(n)} and |
The loop is terminated when the border between @var{limit-sgn(n)} and |
