pa...@compugenic.com wrote:
> On Thu, Sep 24, 2009 at 02:16:05PM -0400, Uri Guttman wrote:
>>>>>>> "p" == pablo <pa...@compugenic.com> writes:
>> p> I have a script that tells me the largest file (in bytes) for each
>> p> extension. I store the largest size in a hash, keyed by the extension.
>>
>> p> The numeric comparison portion is clearly not working, since it is
>> returning true every time regardless of the numbers being compared. Here's
>> a snippet, along with the output shown:
>>
>> p> Snippet:
>> p> if ( $bytes > $sizes{$ext}->{largest} ) {
>>
>> you use 'largest' there. assuming that isn't ever set, this compares
>> bytes to undef. this would have been detected if you had enabled
>> warnings. this is why we always say to make your code warnings
>> clean. there is a reason for this!
>>
>> p> print "$bytes is larger than $sizes{$ext}->{largest_size}\n";
>> p> $sizes{$ext}->{largest_size} = $bytes;
>>
>> and 'largest_size' in those two lines.
>>
>> uri
>>
>
> That's good advice which I always follow. I always use warnings and strict,
> unless testing something.
Using the warnings pragma is especially important when writing tests AFAIC.
> #!/usr/bin/perl
> use strict;
> to
> #!/usr/bin/perl -w
> use strict; # Notice I'm using strict too!
Unless you are using a version of perl that is < 5.6, you should replace
'-w' with 'use warnings;'.
> if ( $bytes > ($sizes{$ext}->{largest}||0) ) {
> print "$bytes is larger than ", $sizes{$ext}->{largest_size} || 0, "\n";
> $sizes{$ext}->{largest_size} = $bytes;
> }
> else {
> print "$bytes is smaller than $sizes{$ext}->{largest_size}\n";
> }
>
> The output was:
> 304785408 is larger than 0
> 407666688 is larger than 304785408
> 595656704 is larger than 407666688
> 597778432 is larger than 595656704
> 568844288 is larger than 597778432
> 157255680 is larger than 568844288
> 512342016 is larger than 157255680
> 616058880 is larger than 512342016
> 728705024 is larger than 616058880
> 6008832 is larger than 728705024
On my machine, when I explicitly set some variables, it works.
You may want to use Data::Dumper to print out some of your vars to
ensure they are set to what you think they are:
#!/usr/bin/perl
use warnings;
use strict;
my $bytes = 30;
my %sizes;
my $ext = 'this';
$sizes{$ext}->{largest} = 320;
$sizes{$ext}->{largest_size} = 340;
if ( $bytes > ($sizes{$ext}->{largest}||0) ) {
print "$bytes is larger than ", $sizes{$ext}->{largest_size} || 0, "\n";
$sizes{$ext}->{largest_size} = $bytes;
}
else {
print "$bytes is smaller than $sizes{$ext}->{largest_size}\n";
}
__END__
Prints:
30 is smaller than 340
I notice that you are comparing $bytes to $sizes{$ext}->{largest} or 0,
then printing '$bytes is larger than... $sizes->{ext}->{largest_size}.
You are then promptly setting largest size in your result.
So, the integer after the "is larger than" in your output is NOT what
you are comparing $bytes to in the first place.
Put a "print Dumper \%sizes" just before the if statement, so you can
get an idea of what exactly 'largest' and 'largest_size' are set to on
each pass. For instance, if $ext is something different on each pass
through the loop, then 'largest' will also be different than what you
may be expecting.
Steve
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