It has been already discussed lot of times. The difference between my and local and 'our' is not 'my' ll help you. Also take a look at my, local and our. Also you have to do Super Search.

In addition, Look into this Variable Scoping in Perl: the basics in Tutorials. It will give more information to you.

See in Super Search before posting any question.

Update : View this Variables and Scoping for variable scoping.

Another interesting source is perlsub, of course. But note that our isn't dealt with as well.

There's really no relation between those functions, and my is the only one which declares variables. In short,

• my creates a lexically scoped variable. That means it only exists within the current block/file. For example,

  {
     my $var;
  }
  # $var no longer exists.
  [download]

• our is the same as no strict 'vars';, except is only affects the specified (package) var or vars. Like use strict, its effect is bound to the current block/file. For example,

  package main;
  
  use strict;
  
  $main::var = 1;
  #$var = 1;              # Error!
  
  {
     $main::var++;
     #$var++;             # Error!
     our $var;            # Disable "strict vars" for $var.
     $var++;              # Same as "$main::var++;"
  }                       # "strict vars" is back on for $var.
  
  {
     $main::var++;
     #$var++;             # Error!
     no strict 'vars';    # Disable "strict vars" for all vars.
     $var++;              # Same as "$main::var++;"
  }                       # "strict vars" is back on for all vars.
  
  print("$main::var\n");  # Prints 5.
  #print("$var\n");       # Error!
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• local saves the current value of a package variable, and restores it when the current block is exited, even if it is exited by exception. For example,

  $main::var = 1;
  
  {
     local $main::var;  # Saves current value of $main::var
                        # and sets new value to undef.
     
     $main::var = 2;
  } # Restores saved value of $main::var.
  
  print("$main::var\n");  # Prints 1.
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  which is the same as

  package main;
  
  our $var;
  $var = 1;
  
  {
     local $var;        # Saves current value of $main::var
                        # and sets new value to undef.
    
     $var = 2;
  } # Restores saved value of $main::var.
  
  print("$var\n");      # Prints 1.
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Now, you're probably wondering when to use lexical variables and when to use package variables.

Again in short, you want to use lexicals whenever possible. There are a few situations that mandate using pacakge variables:

• Package variables are used for global variables which need to be accessed from other modules. For example, @ISA and @EXPORT are package variables.

• Package variables are also used when dynamic scoping is needed, because of local makes it easy to do so. For example,

  sub recursive {
     our $state;
  
     ...
  
     if (...) {
        local $state = ~~~;
        recursive();
     }
  
     ...
  }
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• Package variables are needed for (?{ ... }) and similar constructs in regexps.

• Aliases are created using package variables (except when using some modules). For example,

  my $var = 1;
  our $alias;
  *alias = \$var;
  $alias = 2;
  print("$var\n");   # 2
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The variables in perlvar are package variables, so you can use local on them.

I feel this could give u a lot more information on all the built in function which could be very much handy for you.

perlfunc.

Thank you

Sushil