Hi Corion..

The code is working fine, but not does my intention function...i modified the code for my need based on your comments as followed...

use strict;
use warnings;

open (IN1, "<design_modify1.vhd") or die;
open (OUT, ">output_file.vhd") or die;
open (IN2, "<nets.txt") or die;
open (IN3, "<enabled_nets.txt") or die;
my @nets = <IN2>;
my @enabled_nets = <IN3>;
chomp @nets;
chomp @enabled_nets;
while (<IN1>) {
print OUT;
    foreach my $i (0..$#nets){
        print OUT if (s/\=\>\s+$nets[$i]\,/\=\> $enabled_nets[$i]\,/);
    #}
    
}
close (IN1);
close (OUT);
close (IN2);
close (IN3);
[download]

I want the output file as follows.. (shown only the modifiable lines)

VCC_i : VCC port map(Y => \VCC\);
    
    sum_1_SUM0_0 : XOR3 port map(A => b_e, B => a_e, C => c_e, Y => su
+m_c);
        
    carry_pad : OUTBUF port map(D => N_5, PAD => carry);
    
    a_pad : INBUF port map(PAD => a, Y => a_c);
[download]

but it is printing as follows.. I understood the mistake in the code that since i wrote the print statement inside for loop, it gets only one element of array at a time.. So, do you have any suggestions for this???

VCC_i : VCC port map(Y => \VCC\);
    
    sum_1_SUM0_0 : XOR3 port map(A => b_c, B => a_c, C => c_c, Y => su
+m_c);
    sum_1_SUM0_0 : XOR3 port map(A => b_c, B => a_e, C => c_c, Y => su
+m_c);
    sum_1_SUM0_0 : XOR3 port map(A => b_e, B => a_e, C => c_c, Y => su
+m_c);
    sum_1_SUM0_0 : XOR3 port map(A => b_e, B => a_e, C => c_e, Y => su
+m_c);
    
    carry_pad : OUTBUF port map(D => N_5, PAD => carry);
    
    a_pad : INBUF port map(PAD => a, Y => a_c);
[download]