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comparison doc/interpreter/stmt.txi @ 6501:68f3125f6e27

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[project @ 2007-04-05 20:53:40 by jwe]
author jwe
date Thu, 05 Apr 2007 20:53:40 +0000
parents b2ce28713791
children f80cc454860d
comparison
equal deleted inserted replaced
6500:3ea308b4b37e 6501:68f3125f6e27
191 191
192 @noindent 192 @noindent
193 using the indentation to show how Octave groups the statements. 193 using the indentation to show how Octave groups the statements.
194 @xref{Functions and Scripts}. 194 @xref{Functions and Scripts}.
195 195
196 @DOCSTRING(warn_assign_as_truth_value)
197
198 @node The switch Statement 196 @node The switch Statement
199 @section The @code{switch} Statement 197 @section The @code{switch} Statement
200 @cindex @code{switch} statement 198 @cindex @code{switch} statement
201 @cindex @code{case} statement 199 @cindex @code{case} statement
202 @cindex @code{otherwise} statement 200 @cindex @code{otherwise} statement
290 the labels are integer constants. Perhaps a future variation on this 288 the labels are integer constants. Perhaps a future variation on this
291 could detect all constant integer labels and improve performance by 289 could detect all constant integer labels and improve performance by
292 using a jump table. 290 using a jump table.
293 @end itemize 291 @end itemize
294 292
295 @DOCSTRING(warn_variable_switch_label)
296
297 @node The while Statement 293 @node The while Statement
298 @section The @code{while} Statement 294 @section The @code{while} Statement
299 @cindex @code{while} statement 295 @cindex @code{while} statement
300 @cindex @code{endwhile} statement 296 @cindex @code{endwhile} statement
301 @cindex loop 297 @cindex loop
360 reaches 11. 356 reaches 11.
361 357
362 A newline is not required between the condition and the 358 A newline is not required between the condition and the
363 body; but using one makes the program clearer unless the body is very 359 body; but using one makes the program clearer unless the body is very
364 simple. 360 simple.
365
366 @xref{The if Statement}, for a description of the variable
367 @code{warn_assign_as_truth_value}.
368 361
369 @node The do-until Statement 362 @node The do-until Statement
370 @section The @code{do-until} Statement 363 @section The @code{do-until} Statement
371 @cindex @code{do-until} statement 364 @cindex @code{do-until} statement
372 365
410 @end example 403 @end example
411 404
412 A newline is not required between the @code{do} keyword and the 405 A newline is not required between the @code{do} keyword and the
413 body; but using one makes the program clearer unless the body is very 406 body; but using one makes the program clearer unless the body is very
414 simple. 407 simple.
415
416 @xref{The if Statement}, for a description of the variable
417 @code{warn_assign_as_truth_value}.
418 408
419 @node The for Statement 409 @node The for Statement
420 @section The @code{for} Statement 410 @section The @code{for} Statement
421 @cindex @code{for} statement 411 @cindex @code{for} statement
422 @cindex @code{endfor} statement 412 @cindex @code{endfor} statement
665 Octave expressions or commands. The statements in @var{cleanup} are 655 Octave expressions or commands. The statements in @var{cleanup} are
666 guaranteed to be executed regardless of how control exits @var{body}. 656 guaranteed to be executed regardless of how control exits @var{body}.
667 657
668 This is useful to protect temporary changes to global variables from 658 This is useful to protect temporary changes to global variables from
669 possible errors. For example, the following code will always restore 659 possible errors. For example, the following code will always restore
670 the original value of the built-in variable @code{warn_fortran_indexing} 660 the original value of the global variable @code{frobnositcate}
671 even if an error occurs while performing the indexing operation. 661 even if an error occurs while performing the indexing operation.
672 662
673 @example 663 @example
674 @group 664 @group
675 save_warn_fortran_indexing = warn_fortran_indexing; 665 save_frobnosticate = frobnosticate;
676 unwind_protect 666 unwind_protect
677 warn_fortran_indexing = 1; 667 frobnosticate = true;
678 elt = a (idx) 668 @dots{}
679 unwind_protect_cleanup 669 unwind_protect_cleanup
680 warn_fortran_indexing = save_warn_fortran_indexing; 670 frobnosticate = save_frobnosticate;
681 end_unwind_protect 671 end_unwind_protect
682 @end group 672 @end group
683 @end example 673 @end example
684 674
685 Without @code{unwind_protect}, the value of @var{warn_fortran_indexing} 675 Without @code{unwind_protect}, the value of @var{frobnosticate}
686 would not be restored if an error occurs while performing the indexing 676 would not be restored if an error occurs while performing the indexing
687 operation because evaluation would stop at the point of the error and 677 operation because evaluation would stop at the point of the error and
688 the statement to restore the value would not be executed. 678 the statement to restore the value would not be executed.
689 679
690 @node The try Statement 680 @node The try Statement