Use of uninitialized value in pattern match - regex

Question

I have the following code in a subroutine in Perl for which I keep getting the following error :
Use of uninitialized value $nextLine in pattern match (m//) at catlist.pl line 67, line 2756.
sub extract_testdesc {
my #str = #_;
my $file = $_[0];
my $testname = $_[1];
my #fifo;
# Open the file
open( FILEHANDLE, $file ) or die "couldnt open";
while (<FILEHANDLE>) {
if ( $_ =~ m/\/\*\*/ ) { # if start of comment /**
undef(#fifo);
$nextLine = <FILEHANDLE>;
while ( $nextLine !~ m/\*\// ) { # Add all lines into array until */ is encountered
if ( $nextLine !~ m/\#testlogic.author/ ) {
$nextLine =~ s/\*//g;
if ( $nextLine ne "" ) {
push( #fifo, $nextLine );
}
}
$nextLine = <FILEHANDLE>;
}
}
if ( $_ =~ m/$testname/ ) {
return (#fifo);
}
}
close(FILEHANDLE);
}
What am I doing wrong ? I'm new to Perl so any help is appreciated.

Answer 1

Whenever you use a while loop on a file handle, it's actually synonymous with while (defined($_ = <FILEHANDLE>)) {. This is useful because once the filehandle reaches the eof, it will exit the loop. On the other hand, you are doing manual calls readline calls without testing to see if anything was returned, hence your uninitialized value warnings.
Overall, your goal and logic are confusing. However, perhaps an introduction to the range operator will help you? The following achieves what I think you logic is, but I easily could have misinterpreted.
sub extract_testdesc {
my ($file, $testname) = #_;
my #fifo;
# Open the file
open my $fh, '<', $file or die "couldnt open: $!";
while (<$fh>) {
if ( my $range = m{\Q/**} .. m{\Q*/}) {
#fifo = () if $range == 1;
push #fifo, $_;
} elsif ($_ =~ m/\Q$testname\E/ ) {
return (#fifo);
}
}
close($fh);
}