In the code example, I pass a hash by value to a sub, push_1, and push one onto the array,
@{ $hash{$key} }
But when I examine the hash after the sub call, the changes are in the hash, but why is this happening. I thought the hash should have the pre function call values.
#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
my %hash;
@hash{ 'a'..'d' } = ([175, 450], [0, 350], [0, 50], [300, 50]);
print "Initial hash\n";
print Dumper \%hash;
print "\nhash after call\n";
push_1(%hash);
print Dumper \%hash;
sub push_1 {
my %hash = @_;
for (keys %hash) {
push @{ $hash{$_} }, 1;
}
}
__END__
*** Output
C:\perlp>perl t.pl
Initial hash
$VAR1 = {
'c' => [
0,
50
],
'a' => [
175,
450
],
'b' => [
0,
350
],
'd' => [
300,
50
]
};
hash after call
$VAR1 = {
'c' => [
0,
50,
1
],
'a' => [
175,
450,
1
],
'b' => [
0,
350,
1
],
'd' => [
300,
50,
1
]
};
C:\perlp>
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