Dear Monks,

I recently was surprised that a ascii '0' was interpreted by an if statement as 'FALSE'. I have thought about this alot, and wonder if this really the way it should be.

The following script shows what I'm talking about.

use strict;
my $var = 0;   if ( $var ) { print "$var True\n"; } else { print "$var
+ False\n"; }
undef $var;    if ( $var ) { print "undef True\n"; } else { print "und
+ef False\n"; }
my $var1 = '';  if ( $var1 ) { print "'$var1' True\n"; } else { print 
+"'$var1' False\n"; }
my $var2 = "";  if ( $var2 ) { print "\"$var2\" True\n"; } else { prin
+t "\"$var2\" False\n"; }
        my $var3 = '0'; if ( $var3 ) { print "\t'$var3' True\n"; } els
+e { print "\t'$var3' False\n"; }
        my $var4 = "0"; if ( $var4 ) { print "\t\"$var4\" True\n"; } e
+lse { print "\t\"$var4\" False\n"; }
        if ( $var4 == 0 ) { print "\t\"\$var4\" True\n"; } else { prin
+t "\t\$var4\" False\n"; }
        if ( $var4 eq '0' ) { print "\t\"\$var4\" True\n"; } else { pr
+int "\t\"\$var4\" False\n"; }
        print "\t","\"\$var4\" has length of ",length($var4)," and ASC
+II value of ",ord($var4),"\n";
my $var5 = '1'; if ( $var5 ) { print "'$var5' True\n"; } else { print 
+"'$var5' False\n"; }
my $var6 = "1"; if ( $var6 ) { print "\"$var6\" True\n"; } else { prin
+t "\"$var6\" False\n"; }
my $var7 = 1;   if ( $var7 ) { print "\"$var7\" True\n"; } else { prin
+t "\"$var7\" False\n"; }

[download]
The script produces: 
0 False
undef False
'' False
"" False
        '0' False
        '0' False
        "$var4" True
        "$var4" True
        "$var4" has length of 1 and ASCII value of 48
'1' True
"1" True
"1" True

[download]

The first 4 and the last 3 lines I agree with, but the lines in the middle I have a problem with.

I checked several of my perl books and it seems:

But then in "Programming Perl" Glossary is states 'false In Perl, any value that would look like "" or "0"...' but this disagrees with the definition on page 7.

Am I missing something or has it just been too long of a perl week?

Thank you

"Well done is better than well said." - Benjamin Franklin

In reply to What is the correct definition of False and Null in Perl? by flexvault

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