#!/usr/bin/perl

$dir = "C:\\Users\\user\\Desktop\\test";

opendir DIR, $dir or die "error: cannot open directory \"$dir\" $!";

@files = sort grep (!/^\.$|^\.\.$/, readdir(DIR));

closedir (DIR);

foreach $fl(@files) {

  if($fl =~ m/\.doc/) {
     @a = split(/\.doc/,$fl);
      foreach $len(@a) {
          $z = length $len;
             if($len <= $z) {

                @x = substr($len,0,7); 

                    foreach $mod(@x) {
                       $mod = "A".$mod.".doc";
                        rename $fl,$mod;
                       }    
                  }  
             
             }
      }
}