perl 正则命名捕获

#!/usr/bin/perl -w 
=pod 
命名捕获--给匹配上的内容加上标签 

捕获到的内容都会保存在%+散列中，这个散列的key为对应的标签； 

方便之处就是利于程序扩展和阅读，不用繁琐的一个一个去数括号来获取匹配变量 
=cut 


zjtest7-frontend:/root/perl# cat a2.pl 
use strict; 
my $str = "jack and rose"; 
if ($str =~ /(?<first>\S+) (and|or) (?<second>\S+)/) { 
    my ($first, $second) = ($+{first}, $+{second}); 
    print "$first\n$second\n";  # jack, rose 
} 


zjtest7-frontend:/root/perl# perl a2.pl 
jack
rose


\s  空格,和 [\n\t\r\f] 语法一样  
\s+ 和 [\n\t\r\f]+ 一样  
\S  非空格,和 [^\n\t\r\f] 语法一样  
\S+ 和 [^\n\t\r\f]+ 语法一样  

/******************************************************

zjtest7-frontend:/root/perl# cat a1.pl 
my $str="begin 123.456 end";

if ($str =~/(?<first>\S+)\s+(?<second>\S+)\s+(?<third>\S+)/)
  {
  my ($first, $second,$third) = ($+{first}, $+{second},$+{third});
  print "$first\n$second\n$third\n";  # jack, rose 
} 

zjtest7-frontend:/root/perl# perl a1.pl 
begin
123.456
end


zjtest7-frontend:/root/perl# cat a3.pl 
my $str="begin 123.456 end";
if ($str =~/\s+(?<request_time>\d+(?:\.\d+)?)\s+/){
   my ($request_time) = ($+{request_time});
   print $request_time."\n";};

zjtest7-frontend:/root/perl# perl a3.pl 
123.456