arybase(3pm) [osx man page]

arybase(3pm)						 Perl Programmers Reference Guide					      arybase(3pm)

NAME

       arybase - Set indexing base via $[

SYNOPSIS

	   $[ = 1;

	   @a = qw(Sun Mon Tue Wed Thu Fri Sat);
	   print $a[3], "
";  # prints Tue

DESCRIPTION

       This module implements Perl's $[ variable.  You should not use it directly.

       Assigning to $[ has the compile-time effect of making the assigned value, converted to an integer, the index of the first element in an
       array and the first character in a substring, within the enclosing lexical scope.

       It can be written with or without "local":

	   $[ = 1;
	   local $[ = 1;

       It only works if the assignment can be detected at compile time and the value assigned is constant.

       It affects the following operations:

	   $array[$element]
	   @array[@slice]
	   $#array
	   (list())[$slice]
	   splice @array, $index, ...
	   each @array
	   keys @array

	   index $string, $substring  # return value is affected
	   pos $string
	   substr $string, $offset, ...

       As with the default base of 0, negative bases count from the end of the array or string, starting with -1.  If $[ is a positive integer,
       indices from "$[-1" to 0 also count from the end.  If $[ is negative (why would you do that, though?), indices from $[ to 0 count from the
       beginning of the string, but indices below $[ count from the end of the string as though the base were 0.

       Prior to Perl 5.16, indices from 0 to "$[-1" inclusive, for positive values of $[, behaved differently for different operations; negative
       indices equal to or greater than a negative $[ likewise behaved inconsistently.

HISTORY

       Before Perl 5, $[ was a global variable that affected all array indices and string offsets.

       Starting with Perl 5, it became a file-scoped compile-time directive, which could be made lexically-scoped with "local".  "File-scoped"
       means that the $[ assignment could leak out of the block in which occurred:

	   {
	       $[ = 1;
	       # ... array base is 1 here ...
	   }
	   # ... still 1, but not in other files ...

       In Perl 5.10, it became strictly lexical.  The file-scoped behaviour was removed (perhaps inadvertently, but what's done is done).

       In Perl 5.16, the implementation was moved into this module, and out of the Perl core.  The erratic behaviour that occurred with indices
       between -1 and $[ was made consistent between operations, and, for negative bases, indices from $[ to -1 inclusive were made consistent
       between operations.

BUGS

       Error messages that mention array indices use the 0-based index.

       "keys $arrayref" and "each $arrayref" do not respect the current value of $[.

SEE ALSO

       "$[" in perlvar, Array::Base and String::Base.

perl v5.16.2							    2012-10-11							      arybase(3pm)

Check Out this Related Man Page

ARRAY_SLICE(3)								 1							    ARRAY_SLICE(3)

array_slice - Extract a slice of the array

SYNOPSIS

       array array_slice NULL (array  $array, int  $offset, [int  $length], [bool  $preserve_keys = false])

DESCRIPTION

       array_slice(3) returns the sequence of elements from the array $array as specified by the $offset and $length parameters.

PARAMETERS

	      o $array
		- The input array.

	      o $offset
		-  If  $offset	is  non-negative,  the sequence will start at that offset in the $array. If $offset is negative, the sequence will
		start that far from the end of the $array.

	      o $length
		- If $length is given and is positive, then the sequence will have up to that many elements in it. If the array  is  shorter  than
		the  $length,  then  only the available array elements will be present. If $length is given and is negative then the sequence will
		stop that many elements from the end of the array. If it is omitted, then the sequence will have everything from $offset up  until
		the end of the $array.

	      o $preserve_keys
		-  Note  that array_slice(3) will reorder and reset the numeric array indices by default. You can change this behaviour by setting
		$preserve_keys to TRUE.

RETURN VALUES

	Returns the slice.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.2.4	|						    |
       |	|						    |
       |	|  The default value of the $length  parameter	was |
       |	| changed  to  NULL.  A  NULL$length  now tells the |
       |	| function to use the length of  $array.  Prior  to |
       |	| this	version,  a NULL$length was taken to mean a |
       |	| zero length (nothing will be returned).	    |
       |	|						    |
       | 5.0.2	|						    |
       |	|						    |
       |	|  The optional $preserve_keys parameter was added. |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      array_slice(3) examples

	      <?php
	      $input = array("a", "b", "c", "d", "e");

	      $output = array_slice($input, 2);      // returns "c", "d", and "e"
	      $output = array_slice($input, -2, 1);  // returns "d"
	      $output = array_slice($input, 0, 3);   // returns "a", "b", and "c"

	      // note the differences in the array keys
	      print_r(array_slice($input, 2, -1));
	      print_r(array_slice($input, 2, -1, true));
	      ?>

	      The above example will output:

	      Array
	      (
		  [0] => c
		  [1] => d
	      )
	      Array
	      (
		  [2] => c
		  [3] => d
	      )

SEE ALSO

       array_splice(3), unset(3), array_chunk(3).

PHP Documentation Group 													    ARRAY_SLICE(3)

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arybase(3pm) [osx man page]

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