map - apply a change to a list to get back a new list with the changes
map BLOCK LIST
map EXPR,LIST
Evaluates the
BLOCK or
EXPR for each element of
LIST (locally setting
$_
to each element) and returns the list value composed of the results of each such evaluation. Evaluates
BLOCK or
EXPR in a list context, so each element of
LIST may produce zero, one, or more elements in the returned value.
@chars = map(chr, @nums);
translates a list of numbers to the corresponding characters. And
%hash = map { getkey($_) => $_ } @array;
is just a funny way to write
%hash = (); foreach $_ (@array) { $hash{getkey($_)} = $_; }
Note that, because $_
is a reference into the list value, it can be used to modify the elements of the array. While this is useful and supported, it can cause bizarre results if the
LIST is not a named array. See also
grep for an array composed of those items of the original list for which the
BLOCK or
EXPR evaluates to true.
If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.