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Diffstat (limited to 'doc/gawktexi.in')
| -rw-r--r-- | doc/gawktexi.in | 50 |
1 files changed, 33 insertions, 17 deletions
diff --git a/doc/gawktexi.in b/doc/gawktexi.in index ddb0f5ae..c79dd87f 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -14504,20 +14504,25 @@ awk ' This prints the first three fields of each input record, with one input field per output line. -It isn't possible to -set more than one variable in the -@var{initialization} part without using a multiple assignment statement -such as @samp{x = y = 0}. This makes sense only if all the initial values -are equal. (But it is possible to initialize additional variables by writing -their assignments as separate statements preceding the @code{for} loop.) - @c @cindex comma operator, not supported -The same is true of the @var{increment} part. Incrementing additional -variables requires separate statements at the end of the loop. -The C compound expression, using C's comma operator, is useful in -this context, but it is not supported in @command{awk}. +C and C++ programmers might expect to be able to use the comma +operator to set more than one variable in the @var{initialization} +part of the @code{for} loop, or to increment multiple variables in the +@var{incrememnt} part of the loop, like so: + +@example +for (i = 0, j = length(a); i < j; i++, j--) @dots{} @ii{C/C++, not awk!} +@end example + +@noindent +You cannot do this; the comma operator is not supported in @command{awk}. +There are workarounds, but they are nonobvious and can lead to +code that is difficult to read and understand. It is best, therefore, +to simply write additional initializations as separate statements +preceding the @code{for} loop and to place additional increment statements +at the end of the loop's body. -Most often, @var{increment} is an increment expression, as in the previous +Most often, @var{increment} is an increment expression, as in the earlier example. But this is not required; it can be any expression whatsoever. For example, the following statement prints all the powers of two between 1 and 100: @@ -42123,7 +42128,7 @@ The following things are @emph{not} bugs, and should not be reported to the bug mailing list. You can ask about them on the ``help'' mailing list (@pxref{Asking for help}), but don't be surprised if you get an answer of the form ``that's how @command{gawk} behaves and it isn't -going to change.'' +going to change.'' Here's the list: @itemize @bullet @item @@ -42133,6 +42138,8 @@ fields or records, or anything else. The number of features that @command{gawk} does @emph{not} have is by definition infinite. It cannot be all things to all people. +In short, just because @command{gawk} doesn't do what @emph{you} +think it should, it's not necessarily a bug. @item Behaviors that are defined by the POSIX standard and/or for historical @@ -42146,10 +42153,16 @@ and @command{gawk} stand on their own and do not have to follow the crowd. This is particularly true when the requested behavior change would break backwards compatibility. +This applies also to differences in behavior between @command{gawk} +and other language compilers and interpreters, such as wishes for more +detailed descriptions of what the problem is when a syntax error is +encountered. + @item Documentation issues of the form ``the manual doesn't tell me how to do XYZ.'' The manual is not a cookbook to solve every little problem -you may have. +you may have. Its purpose is to teach you how to solve your problems +on your own. @item General questions and discussion about @command{awk} programming or @@ -42178,7 +42191,7 @@ time and ours. @item Verify that you have the latest version of @command{gawk}. Many bugs (usually subtle ones) are fixed at each release, and if yours -is out of date, the problem may already have been solved. +is out-of-date, the problem may already have been solved. @item Please see if setting the environment variable @env{LC_ALL} @@ -42284,6 +42297,10 @@ Usenet/Internet newsgroup @code{comp.lang.awk}. Although some of the @command{gawk} maintainer no longer does. Thus it's virtually guaranteed that he will @emph{not} see your posting. +If you really don't care about the previous paragraph and continue to +post bug reports in @code{comp.lang.awk}, then understand that you're +not reporting bugs, you're just whining. + Similarly, posting bug reports or questions in web forums (such as @uref{https://stackoverflow.com/, Stack Overflow}) may get you an answer, but it won't be from the @command{gawk} maintainers, @@ -42408,7 +42425,7 @@ After two such requests you will be silently @emph{blacklisted} from the bug lis Please note: As with the bug list, we ask that you follow the @uref{https://gnu.org/philosophy/kind-communication.html, -GNU Kind Communication Guidelines} in your correspondence on the +GNU Kind Communication Guidelines} in your correspondence on the help list (as well as off of it). @cindex Proulx, Bob @@ -42416,7 +42433,6 @@ If you wish to the subscribe to the list, in order to help out others, or to learn from others, here are instructions, courtesy of Bob Proulx: - @table @emph @item Subscribe by email |