What does @_ mean at the beginning of code in Perl?

A::(tmp:7):     our $_ = 1;
  DB<9> V :: _
@_ = (
   0  0
   1  '_'
   2  *main::_
   3  0
   4  '-1'
)
  DB<10>

The above is the output of V :: _ at the 1开发者_C百科st line of code,what does @_ mean?

@_ is the variable that holds a subroutine's parameters. When you look at it with V in the debugger, it seems to show the parameters for some internal-to-the-debugger subroutine.

The latest versions of perldoc let you look up variables with the -v switch, which extracts just the part you need from perlvar:

  $ perldoc -v '@_'
   @ARG
   @_      Within a subroutine the array @_ contains the parameters passed
           to that subroutine.  See perlsub.

http://perldoc.perl.org/perlvar.html#General-Variables

Within a subroutine the array @_ contains the parameters passed to that subroutine. Inside a subroutine, @_ is the default array for the array operators push, pop, shift, and unshift

In essence, @_ is the array equivalent of $_

use Data::Dumper;

foo(0,'_',*main::_,0,-1);

sub foo {
   print Dumper(\@_);
}

Outputs:

$VAR1 = [
          0,
          '_',
          *::_,
          0,
          -1
        ];