Re: "last" not really outside loop block

The tricky thing here is that do { ... } while (); is not a single syntax like in C. The do {} is one statement (and not a loop, which is a little confusing) and the postfix while just repeats this like any other statement.

Funnily, simple braces { } qualify as a 'loop' which is processed once. It can be aborted using last.

Therefore you could use:

$a = 3;
{
    last unless $a == 4;
    redo; # if ( ... );
}
[download]

which works without an error message. But it isn't very good style. Try to use a normal while loop instead.

Supplement:
The perldoc entry for do also gives you the answer and a link to alternative strategies:

do BLOCK
               Not really a function.  Returns the value of the last c
+ommand in the sequence of commands indicated by BLOCK.  When modified
+ by the "while" or "until" loop modifier, executes the BLOCK
               once before testing the loop condition. (On other state
+ments the loop modifiers test the conditional first.)

               "do BLOCK" does not count as a loop, so the loop contro
+l statements "next", "last", or "redo" cannot be used to leave or res
+tart the block.  See [doc://perlsyn] for alternative strategies.
[download]

Comment on Re: "last" not really outside loop block Select or Download Code

Replies are listed 'Best First'.
Re^2: "last" not really outside loop block by spx2 (Deacon) on Jun 22, 2009 at 15:55 UTC
Try to use a normal while loop instead. I kind of need the post-condition and while only gives me pre-condition	[reply]
Re^3: "last" not really outside loop block by mscharrer (Hermit) on Jun 22, 2009 at 15:59 UTC
Try the follwing: Instead of: `do { ... } while (expr);` [download] use: `while (1) { ... last unless (expr); }` [download]	[reply] [d/l] [select]


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