How can I print the contents of a hash in Perl

Question

I keep printing my hash as   of buckets     allocated  How do I print the contents of my hash    Without using a while loop would be most preferable  for example  a one-liner would be best

User · Answer

Data  Dumper is your friend   use Data  Dumper  my  hash     abc    gt  123   def    gt   4 5 6    print Dumper   hash     will output   VAR1                def    gt                         4                       5                       6                                  abc    gt  123

User · Answer

Looping   foreach keys  my hash    print        my hash     n       Functional  map  print        my hash     n     keys  my hash    But for sheer elegance  I d have to choose wrang-wrang s  For my own code  I d choose my foreach  Or tetro s Dumper use

User · Answer

Here how you can print without using Data  Dumper    print      hash

User · Answer

The answer depends on what is in your hash   If you have a simple hash a simple  print map        h     n    keys  h    or  print      h     n  for keys  h    will do  but if you have a hash that is populated with references you will something that can walk those references and produce a sensible output   This walking of the references is normally called serialization   There are many modules that implement different styles  some of the more popular ones are    Data  Dumper Data  Dump  Streamer YAML  XS JSON  XS XML  Dumper   Due to the fact that Data  Dumper is part of the core Perl library  it is probably the most popular  however  some of the other modules have very good things to offer

User · Answer

I really like to sort the keys in one liner code   print       gt   my hash     n  for  sort keys  my hash

User · Answer

The easiest way in my experiences is to just use Dumpvalue   use Dumpvalue      my  hash     key   gt   value   foo   gt   bar     my  dumper   new DumpValue     dumper- gt dumpValue   hash     Works like a charm and you don t have to worry about formatting the hash  as it outputs it like the Perl debugger does  great for debugging    Plus  Dumpvalue is included with the stock set of Perl modules  so you don t have to mess with CPAN if you re behind some kind of draconian proxy  like I am at work

User · Answer

My favorite  Smart  Comments  use Smart  Comments              hash   That s it

User · Answer

I append one space for every element of the hash to see it well   print map             h    n

User · Answer

For debugging purposes I will often use YAML   use strict  use warnings   use YAML   my  variable     abc    gt  123   def    gt   4 5 6     print     variable n   Dump   variable    Results in      variable --- abc  123 def    - 4   - 5   - 6     Other times I will use Data  Dump  You don t need to set as many variables to get it to output it in a nice format than you do for Data  Dumper   use Data  Dump    dump    print dump   variable     n         abc   gt  123  def   gt   4  5  6        More recently I have been using Data  Printer for debugging   use Data  Printer  p  variable            abc   123      def              0  4           1  5           2  6             Result can be much more colorful on a terminal    Unlike the other examples I have shown here  this one is designed explicitly to be for display purposes only  Which shows up more easily if you dump out the structure of a tied variable or that of an object   use strict  use warnings   use MTie  Hash  use Data  Printer   my  h   tie my  h   Tie  StdHash    h  a    d    A    D   p  h  print   n   p  h            a    A       b    B       c    C       d    D     tied to Tie  StdHash   Tie  StdHash        public methods  9    CLEAR  DELETE  EXISTS  FETCH  FIRSTKEY  NEXTKEY  SCALAR  STORE  TIEHASH     private methods  0      internals            a    A           b    B           c    C           d    D

User · Answer

Easy    print      h     n  for  keys  h     Elegant  but actually 30  slower       while  my   k  v  each  h  print   k  v n

User · Answer

If you want to be pedantic and keep it to one line  without use statements and shebang   then I ll sort of piggy back off of tetromino s answer and suggest   print Dumper     abc    gt  123   def    gt   4 5 6         Not doing anything special other than using the anonymous hash to skip the temp variable

[perl] How can I print the contents of a hash in Perl?

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