Your suggestion to turn on -w is absolutely right, but we should right the way apply it in this particular case.

Just a small correction ;-) For $a--, you said, "undef prints as the empty string", that's not quite right. The fact is Perl didn't print anything, and simply ignored that print $a--, because it attempted to print an uninitialized value.

This would become clear, if you try this:

Step 1:

Put this in a file, say test.pl: 
print $a--;

[download]
Step 2:

Run it by typing perl -w test.pl, and you will get the warning, so perl never printed it as empty string, instead issued a waring. However when you run it as one-liner, the warning is not printed.

So the bug (inconsistancy) is not that, in the -- case, perl see $a as string; in the ++ case, perl see $a as number.

The bug (inconsistancy) is that, in the -- case, perl straightly realized $a is uninitialized; in the ++ case, perl initialized it to 0.

In reply to Re: Re: dumb question by pg
in thread post-increment and post-decrement behavior (was: dumb question) by Anonymous Monk

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