From 56d7751aa4c2e1e56296cbd71ecc38fb6fe74276 Mon Sep 17 00:00:00 2001 From: Gurusamy Sarathy Date: Tue, 15 Feb 2000 17:05:12 +0000 Subject: doc patches from Rick Delaney and Chris Nandor; update Todo-5.6 p4raw-id: //depot/perl@5102 --- pod/perldata.pod | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) (limited to 'pod/perldata.pod') diff --git a/pod/perldata.pod b/pod/perldata.pod index 0b83214a73..a122d34c80 100644 --- a/pod/perldata.pod +++ b/pod/perldata.pod @@ -600,16 +600,16 @@ of how to arrange for an output ordering. =head2 Slices -A common way access an array or a hash is one scalar element at a time. -You can also subscript a list to get a single element from it. +A common way to access an array or a hash is one scalar element at a +time. You can also subscript a list to get a single element from it. $whoami = $ENV{"USER"}; # one element from the hash $parent = $ISA[0]; # one element from the array $dir = (getpwnam("daemon"))[7]; # likewise, but with list A slice accesses several elements of a list, an array, or a hash -simultaneously using a list of subscripts. It's a more convenient -that writing out the individual elements as a list of separate +simultaneously using a list of subscripts. It's more convenient +than writing out the individual elements as a list of separate scalar values. ($him, $her) = @folks[0,-1]; # array slice @@ -633,8 +633,8 @@ The previous assignments are exactly equivalent to ($folks[0], $folks[-1]) = ($folks[0], $folks[-1]); Since changing a slice changes the original array or hash that it's -slicing, a C construct will alter through some--or even -all--of the values of the array or hash. +slicing, a C construct will alter some--or even all--of the +values of the array or hash. foreach (@array[ 4 .. 10 ]) { s/peter/paul/ } @@ -644,15 +644,16 @@ all--of the values of the array or hash. s/(\w+)/\u\L$1/g; # "titlecase" words } -You couldn't just loop through C to do this because -that function produces a new list which is a copy of the values, -so changing them doesn't change the original. - A slice of an empty list is still an empty list. Thus: @a = ()[1,0]; # @a has no elements @b = (@a)[0,1]; # @b has no elements - @b = (1,undef)[1,0,1]; # @b has three elements + @c = (0,1)[2,3]; # @c has no elements + +But: + + @a = (1)[1,0]; # @a has two elements + @b = (1,undef)[1,0,2]; # @b has three elements This makes it easy to write loops that terminate when a null list is returned: -- cgit v1.2.1