You can change your loop code to be as follows: 
for($i = 0; $i < @contents; $i++){
      if($contents{$i] =~ m/manager\.(\d*)\.address=(\d*\.\d*\.\d*\.\d
+*)/) {
       if($address eq "$2"){
            print "manager.$1.address=$2\n";
            print " exist at index $i\n";
        }
   }
}

[download]
-albert

Update: editing the suggestion for the lack of $_ in the solution. Untested code, your mileage may vary.

In reply to Re: to find an index of a particular value in an array by albert
in thread to find an index of a particular value in an array by s_gaurav1091

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