perl正則命名分組捕獲__perl

1、命名分組格式為(?<grp name>)，反向引用時用\k<grp name>

2、命名分組的匹配的結果存在在變數%+變數中，取命名分組值，$+{grp name}.

3、反向引用也可以用\g1,\g{1},\g{-1},\g{-2}等，負表示分組的倒數每幾個分組.

例：

方法1：

local $_  ='Buster and buster';
if(/(\S+) (and|or) \1/i)
{
print "I found the same name twice:$1\n";
print "\$2=$2\n";
}
else
{
print "not matched\n";
}


#-----------------------------------------------------------

方法2：
local $_  ='Buster and buster';
if(/(?<key>\S+) (and|or) \k<key>/i)
{
print "I found the same name twice:$+{key}\n";
print "\$2=$2\n";
}
else
{
print "not matched\n";
}
#-----------------------------------------------------------

方法3：
local $_  ='Buster and buster';
if(/(?<key>\S+) (?:and|or) \g{-1}/i)
{
print "I found the same name twice:$+{key}\n";
}
else
{
print "not matched\n";
}