Not in order in Hash output

[truthseeker66]

When I run this script why do I get the keys and values not in order?
Thank you,

#!/usr/bin/perl
use strict;
use warnings;

my%hash1 = ("a",1,"b",2,"c",3,"d",4);
while (my@values = each(%hash1)){
    print "The key/value pair is @values \n";
    }

C:\JPARK\JPERL>test.pl
The key/value pair is c 3
The key/value pair is a 1
The key/value pair is b 2
The key/value pair is d 4

[toolic]

perlintro

Hashes have no particular internal order, though you can sort the keys and loop through them.

See also:

• sort
• keys
• FAQ: perldoc -q hash

[aitap]

perldoc perldata:

Note that just because a hash is initialized in that order doesn't mean that it comes out in that order. See "sort" in perlfunc for examples of how to arrange for an output ordering.

[ikegami]

Just like arrays, hash return their elements in the order they are physically arranged in the hash. Hashes differ from arrays in that one cannot control the order in which elements are arranged, and the order can change whenever the number of hash element changes.

[perl_walker]

Try this,

use strict;
use warnings;
use Tie::IxHash;

my %hash1 = ();
tie %hash1, "Tie::IxHash";
%hash1 = ("a",1,"b",2,"c",3,"d",4);

while (my@values = each(%hash1)){
    print "The key/value pair is @values \n";
    }

[MidLifeXis]

Just a couple comments on the coding style I have seen you use in many of your posts.

• my is a token separate from the name of the variable. Whitespace can help with readability. The formatting that you seem to prefer (my$var ...) is not one that I typically see, is unexpected, and (at least for me) causes a break in the flow while mentally parsing the code. More typical is my $var ....
• When assigning to a hash, it can be more readable to write %hash = ( a => 1, b => 2, c => 3, ... ). The 'fat comma' is another indicator to my synaptic-based parser that this is a hash assignment.

Nothing that is end-of-the-world type stuff, but more indicators to help my future-self understand what I was thinking when I originally wrote the code.

[johngg]

You could also investigate Tie::IxHash.