I coded the following myscript.pl … 

#!/usr/bin/perl
$|=1;

my %arguments;

for( my $arg = 0 ; $arg <= $#ARGV ; $arg++ ) {
    print $ARGV[$arg]."\n";
    $arguments{ $arg } = $ARGV[$arg];
    foreach my $arg ( %arguments ) {
        print "key = >$arg< value = >$arguments{$arg}<\n";
    }
}

[download]

If I run the script like so…

myscript.pl arg1 arg2 agr3

I get the following output.

arg1
key = >0< value = >arg1<
key = >arg1< value = ><
arg2
key = >0< value = >arg1<
key = >arg1< value = ><
key = >1< value = >arg2<
key = >arg2< value = ><
arg3
key = >0< value = >arg1<
key = >arg1< value = ><
key = >1< value = >arg2<
key = >arg2< value = ><
key = >2< value = >arg3<
key = >arg3< value = ><

If I include use strict, I get the error "Use of uninitialized value in concatenation (.) or string at ./myscript.pl line 13." preceeding the print of the element that has the value as the key and no value.

I went a googling and did a search here at the Monistary but was unable to find an answer to the mystery. Can you help me to understand why the hash has a key/value pair of the real key and value, then a key/value pair with the real value as the key and no value to go with it?

In reply to hash{X}=array[X] results in two hash keys by lucastas

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