How to get rid of the syntax error in this code? - perl

Question

Below I'v proided just a chunk of a huge perl script I am trying to write. I am getting syntax errors in else statement but in the console window its only saying syntax error at perl script and not clearly telling the error. I am trying to create a variable file file_no_$i.txt and copy contents of t_code.txt in it and then find and replace string in the variable file with some selected keys of hash %defines_2
open ( my $pointer, "<", "t_code.txt" ) or die $!;
my $out_pointer;
for (my $i=0 ; $i <=$#match ; $i++) {
for (my $j=0; $j <= $#match ; $j++) {
if ($match[$i]=~$match[$j]) {
next;
}
else {
my $file_name = "file_no_$i.txt";
open $out_pointer, ">" , $file_name or die "Can't open the output file!";
copy("$file_name","t_code.txt") or die "Copy failed: $!";
my #lin = <$out_pointer>;
foreach $_(#lin) {
$_ =~ s/UART90_BASE_ADDRESS/$defines_2{ $_ = grep{/$match[$i]/} (keys %defines_2)};
}
}
}
}

Answer 1

You cannot use / unquoted inside a s/// construct. Instead of backslashes, you can use different delimiters:
s#UART90_BASE_ADDRESS#$defines_2{ $_ = grep{/$match[$i]/} (keys %defines_2)}#;
It fixes the syntax error, but I fear it still won't do what you want. Without data, it's hard to test, though.

Answer 2

What I think you're doing is editing a number of text files whose names look like file_no_1.txt etc. You're doing that by copying the current file to t_code.txt and then reading that file line by line, editing as required, as writing the lines back to the original text file.
The problem with that approach is that the file will be copied and rewritten many times, and it would be better to read the whole file into an array, make all the edits, and then write them back in one operation. That would be fine unless the file is enormous — say, several GB.
Here's some code that implements that approach. You see that $file_name is defined and #lines is filled outside the inner loop. The innermost loop modifies the elements of #lines and, outside that loop again, #lines is written back to the original text file.
I couldn't fathom a couple of things about your code.
I'm not sure if you should be using =~ or if you intended a simple eq. The former does a contains test, and you had a problem in the past where you meant to check that the first string had the second at the end
The grep call
grep{/$match[$i]/} (keys %defines_2)
worries me, as it can potentially return more than one key of the %defines_2 hash, in which case your own code will insert what is pretty much a random selection from the hash elements
If your code is working then that's fine, but if not then I hope this helps you fix it. If you need more help on this chunk of code then you should include a small sample of the data so that we can better understand what is going on.
for my $i (0 .. $#match) {
my $file_name = "file_no_$i.txt";
my #lines = do {
open my $in_fh, '<', 't_code.txt' or die $!;
<$in_fh>;
};
for my $j (0 .. $#match) {
next if $match[$i] =~ $match[$j];
for ( #lines ) {
my ($match) = grep { /$match[$i]/ } keys %defines_2;
s/UART90_BASE_ADDRESS/$defines_2{$match}/;
}
}
open my $out_fh, '>', $file_name or die qq{Can't open "$file_name" for output: $!};
print $out_fh $_ for #lines;
close $out_fh or die qq{Failed to close output file "$file_name": $!};
}