关于while循环嵌套的例子

#!/usr/bin/perl -w
use strict;
############ while嵌套循环，内循环中需要打开的文件在内循环中打开
my $ori_mc_config="c:\\tower\\lmsetup\\mc_config_org.txt";
my $mc_config="c:\\tower\\lmsetup\\mc.txt";
my $newfile="c:\\tower\\lmsetup\\mc_config.txt";
#open OLD, "$ori_mc_config"|| die "can't open the file $!";
open NEWF ,">$mc_config"||die "can't open the fiel $!";
open NEWP ,$newfile;
while(my $line=){
#print $line;
if($line=~/^[A-Z]/){             #print out comment lines.If the line start with character A~Z(may commond line)
$line=~/=/;   
my $d=$`; 
 open OLD, "$ori_mc_config"|| die "can't open the file $!";#内循环中打开文件句柄，如果在外循环中打开，则只匹配一次即退出
while(my $old=){              #check old files the configration lines
if($old=~/^[A-Z]/){
if ($old=~/$d/){
#   print $old;
}
}
}  
close OLD;
  
}
else {print $line;}                            #comment lines
}