#!/usr/bin/perl
#
$txt="1234ab56";
$txt =~ /\d\d/g;
print "matched $&: ",pos $txt,"\n";
$txt =~ /\d\d/g;
print "matched $&: ",pos $txt,"\n";
$txt =~ /\G\d/gc;        # 匹配失败，指针卡在原地
print "matched $&: ",pos $txt,"\n";
$txt =~ /\G\d/gc;        # 匹配失败，指针继续卡在原地
print "matched $&: ",pos $txt,"\n";
$txt =~ /\G\d/gc;        # 匹配失败，指针继续卡在原地
print "matched $&: ",pos $txt,"\n";