FyD wrote:
> Hi,
>
> Here is a short perl script:
>
> open (FILE, "<$START");
First of all, we ALWAYS recommend you put "use strict" at the top of your
program and delcare your variables with "my". That can save you from lots of
trouble with typos, etc. Also, always check the return value from calls like
open(), etc. Where did $START come from?
> $nbc=0;
> foreach(<FILE>){
> if (/^XXX/ig) { $atmnb[$nbc]++;}
> if (/^YYY/ig) { $atmnb1=$atmnb[0];}
> if (/^ZZZ/ig) { $nbc++;}
> }
> if ($atmnb1 eq "") { $atmnb1=$atmnb[0];}
> close(FILE);
> $nbc++;
>
> When I try to execute it using the '-w' option, I get the following
> warning: "Use of uninitialized value in string eq at RED-II.pl line 8"
>
> I do not understand as for me ($atmnb1 eq "") is needed for
> uninitialized values.
>
> How can avoid such warnings ?
The warning happens because $atmnbl has (apparently) never been initialized,
so it has the value undef for the purposes of the comparison. When undef is
used in an eq comparison, it's treated as an empty string, so your
comparison will work OK.
I personally find that particular warning extremely annoying, because you
often have to jump through a number of unnecessary hoops to avoid it.
Fortunately, with recent versions of Perl you can selectively disable this
warning with:
no warnings 'uninitialized';
You might want to use the defined() function instead. That will get rid of
the warning.
if (!defined($atmnb1)) { $atmnb1=$atmnb[0];}
Which is written more idiomatically as:
$atmnbl = $atmnb[0] unless defined $atmnbl;
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