perlfunc
gods
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map - apply a change to a list to get back a new list with the changes
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map
<FONT SIZE=-1>BLOCK</FONT>
<FONT SIZE=-1>LIST</FONT>
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map
<FONT SIZE=-1>EXPR,LIST</FONT>
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Evaluates the
<FONT SIZE=-1>BLOCK</FONT> or
<FONT SIZE=-1>EXPR</FONT> for each element of
<FONT SIZE=-1>LIST</FONT> (locally setting
<CODE>$_</CODE> to each element) and returns the list value composed of the results of each such evaluation. Evaluates
<FONT SIZE=-1>BLOCK</FONT> or
<FONT SIZE=-1>EXPR</FONT> in a list context, so each element of
<FONT SIZE=-1>LIST</FONT> may produce zero, one, or more elements in the returned value.
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<PRE> @chars = map(chr, @nums);
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translates a list of numbers to the corresponding characters. And
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<PRE> %hash = map { getkey($_) => $_ } @array;
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is just a funny way to write
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<PRE> %hash = ();
foreach $_ (@array) {
$hash{getkey($_)} = $_;
}
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Note that, because <CODE>$_</CODE> 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
<FONT SIZE=-1>LIST</FONT> is not a named array. See also
[perlfunc:grep|grep] for an array composed of those items of the original list for which the
<FONT SIZE=-1>BLOCK</FONT> or
<FONT SIZE=-1>EXPR</FONT> evaluates to true.
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