Perl中的grep和map

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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 -wuse strict;#get positive numbermy @number = (1,2,3, -1,-5);my @positive_number = grep  $_ > 0, @number;print "\@number: (@number)\n";print "\@positive_number: (@positive_number)\n";#get sqrtmy @sqrt_number  = map sqrt $_, @positive_number;print "\@sqrt_number: (@sqrt_number)\n";#split wordsmy @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 addressmy @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