Mercurial > octave-nkf

comparison doc/interpreter/stmt.txi @ 3489:cbee5fbb696d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
[project @ 2000-01-28 09:14:32 by jwe]
author jwe
date Fri, 28 Jan 2000 09:14:34 +0000
parents 9610d364e444
children aae05d51353c
comparison
equal deleted inserted replaced
3488:85c0ebb78d1e 3489:cbee5fbb696d
33 33
34 @menu 34 @menu
35 * The if Statement:: 35 * The if Statement::
36 * The switch Statement:: 36 * The switch Statement::
37 * The while Statement:: 37 * The while Statement::
38 * The do-until Statement::
38 * The for Statement:: 39 * The for Statement::
39 * The break Statement:: 40 * The break Statement::
40 * The continue Statement:: 41 * The continue Statement::
41 * The unwind_protect Statement:: 42 * The unwind_protect Statement::
42 * The try Statement:: 43 * The try Statement::
291 using a jump table. 292 using a jump table.
292 @end itemize 293 @end itemize
293 294
294 @DOCSTRING(warn_variable_switch_label) 295 @DOCSTRING(warn_variable_switch_label)
295 296
296 @node The while Statement, The for Statement, The switch Statement, Statements 297 @node The while Statement, The do-until Statement, The switch Statement, Statements
297 @section The @code{while} Statement 298 @section The @code{while} Statement
298 @cindex @code{while} statement 299 @cindex @code{while} statement
299 @cindex @code{endwhile} statement 300 @cindex @code{endwhile} statement
300 @cindex loop 301 @cindex loop
301 @cindex body of a loop 302 @cindex body of a loop
363 simple. 364 simple.
364 365
365 @xref{The if Statement}, for a description of the variable 366 @xref{The if Statement}, for a description of the variable
366 @code{warn_assign_as_truth_value}. 367 @code{warn_assign_as_truth_value}.
367 368
368 @node The for Statement, The break Statement, The while Statement, Statements 369 @node The do-until Statement, The for Statement, The while Statement, Statements
370 @section The @code{do-until} Statement
371 @cindex @code{do-until} statement
372
373 The @code{do-until} statement is similar to the @code{while} statement,
374 except that it repeatedly executes a statement until a condition becomes
375 true, and the test of the condition is at the end of the loop, so the
376 body of the loop is always executed at least once. As with the
377 condition in an @code{if} statement, the condition in a @code{do-until}
378 statement is considered true if its value is non-zero, and false if its
379 value is zero. If the value of the conditional expression in a
380 @code{do-until} statement is a vector or a matrix, it is considered
381 true only if @emph{all} of the elements are non-zero.
382
383 Octave's @code{do-until} statement looks like this:
384
385 @example
386 @group
387 do
388 @var{body}
389 until (@var{condition})
390 @end group
391 @end example
392
393 @noindent
394 Here @var{body} is a statement or list of statements that we call the
395 @dfn{body} of the loop, and @var{condition} is an expression that
396 controls how long the loop keeps running.
397
398 This example creates a variable @code{fib} that contains the first ten
399 elements of the Fibonacci sequence.
400
401 @example
402 @group
403 fib = ones (1, 10);
404 i = 2;
405 do
406 i++;
407 fib (i) = fib (i-1) + fib (i-2);
408 until (i == 10)
409 @end group
410 @end example
411
412 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
414 simple.
415
416 @xref{The if Statement}, for a description of the variable
417 @code{warn_assign_as_truth_value}.
418
419 @node The for Statement, The break Statement, The do-until Statement, Statements
369 @section The @code{for} Statement 420 @section The @code{for} Statement
370 @cindex @code{for} statement 421 @cindex @code{for} statement
371 @cindex @code{endfor} statement 422 @cindex @code{endfor} statement
372 423
373 The @code{for} statement makes it more convenient to count iterations of a 424 The @code{for} statement makes it more convenient to count iterations of a