Perl中的grep和map

grep返回一个数字中符合条件的所有元素；map对数字中所有元素实施转化并返回结果。两者都遍历了数组，但一个用来搜索，一个用来转化。两者都支持表达式或者代码块。#!/usr/bin/perl -w use strict; #get positive number my @number = (1,2,3, -1,-5); my @positive_number = grep $_ > 0, @number; print "\@number: (@number)\n"; print "\@positive_number: (@positive_number)\n"; #get sqrt my @sqrt_number = map sqrt $_, @positive_number; print "\@sqrt_number: (@sqrt_number)\n"; #split words my @lines = ( "hello world", "not too bad" ); my @words = map m/\b(\w+)\b/g, @lines; print "\@lines size: " . @lines . " (@lines)\n"; print "\@words size: " . @words . " (@words)\n"; #modify email address my @email_addresses = ( "fei\@gmail.com", "fei\@sina.com.cn" ); my @disguised_addresses = map { my $email = $_; $email =~ s/\@/ at /; $email =~ s/\./ dot /g; $email; } @email_addresses; print "\@email_addresses: (@email_addresses)\n"; print "\@disguised_addresses: (@disguised_addresses)\n";
参考：http://mailman.linuxchix.org/pipermail/courses/2003-November/001368.html