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Old 02-13-2019, 09:38 AM   #1
new_user3085
LQ Newbie
 
Registered: Sep 2016
Posts: 16

Rep: Reputation: Disabled
Reference to a function


Hi All,

Could you look at the below script and help me understand why the output is in reverse order.

Code:
lab@a128:~/mydir> cat ref2fn
#!/usr/bin/perl
# Function definition
sub PrintHash {
    my (%hash) = @_;

    foreach $item (%hash) {
        print "Item: $item\n";
    }
}
%hash = ('name' => 'Tom', 'age' => 19);
%hash1 = ('name' => 'Tommy', 'age' => 39, 'location' => 'Utah');

#Create a reference to above function.
$cref = \&PrintHash; #Uncomment after test
$cref1 = &PrintHash(%hash1);
print "Valud of \$cref is: $cref\n";

#Function call using reference.
&$cref(%hash);  #Uncomment after test
&$cref1(%hash1);  #Uncomment after test
lab@a128:~/mydir> ./ref2fn
Item: location
Item: Utah
Item: name
Item: Tommy
Item: age
Item: 39
Valud of $cref is: CODE(0x7b3f20)
Item: name
Item: Tom
Item: age
Item: 19
Undefined subroutine &main:: called at ./ref2fn line 20.

lab@a128:~/mydir>

I was expecting the below output to print first

Code:
Item: name
Item: Tom
Item: age
Item: 19
Why is this so? Please explain.
Also, it's complaining
Code:
Undefined subroutine &main:: called at ./ref2fn line 20.
in the last line of the output. What is it complaining about?

Thanks in advance!! Appreciate your time.

Last edited by new_user3085; 02-13-2019 at 09:41 AM.
 
Old 02-13-2019, 09:44 AM   #2
pan64
LQ Guru
 
Registered: Mar 2012
Location: Hungary
Distribution: debian/ubuntu/suse ...
Posts: 12,606

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probably you missed a backslash here: $cref1 = \&PrintHash(%hash1)
This will cause what you asked.

the order of items in a hash is not specified, it is more or less random.
 
  


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