Sorry if my question is too obvious, I´m new in perl.
My code is the following:
open (FILE1, "$ARG[0]") or die
#lines1;
$i=1;
while (<FILE>) {
chomp;
push (#lines1, $_);
my #{columns$1}= split (/\s+/, $lines1[$i]);
$i++;
}
It gives an error saying
Can´t declare array dereference at the line my #{columns$1}= split (/\s+/, $lines1[$i]);
I wanted to create columns1, columns2, columns3... and each one of them would have the columns of the corresponding line (columns1 of the line 1, columns2 of line 2 and so on...)
Because before I tried to do it this way (below) and every time it was splitting the lines but it was overwriting the #columns1 array so only the last line was saved, at the end I had the values of the 10th line (because it starting counting at 0)
for my $i (0..9) {
#columns1 = split (/\s+/, $lines1[$i]);
}
To split a table file in its columns, you could do the following:
#!/usr/bin/perl
#ALWAYS put 'use warnings' and 'use strict' on the beginning of your code. It makes
#your life easier when debugging your code, and save you from having empty variables
#making weird things all over your code, and many other things.
#It is a good practice for "safe Perl coding".
use warnings;
use strict;
my ($file) = #ARGV;
open(my $in, "<$ARGV[0]"); #In your code you used an old filehandle format, FILE1.
#You should use the new format - $file1 as it allows you
#to use any scalar variable as a filehandle.
my #column1;
while(<$in>) {
chomp;
#Here comes the splitting:
my #table = split(/\s+/);
#if you want to print the first column:
print "$table[0]\n"; #remember that Perl starts to count from 0;
#if you know which columns you want to work with:
push(#column1, $table[0]);
}
Even though I am an adept of the do-first-and-learn-to-code-by-fixing-your-mistakes approach to learn to code, you should really take some time to work through the basics of Perl, as #mpapec said. Learn the basics will save a lot of time and effort when dealing with problems like yours.
Related
I am dealing with very large amounts of data. Every now and then there is a slip up. I want to identify each row with an error, under a condition of my choice. With that I want the row number along with the line number of each erroneous row. I will be running this script on a handful of files and I will want to output the report to one.
So here is my example data:
File_source,ID,Name,Number,Date,Last_name
1.csv,1,Jim,9876,2014-08-14,Johnson
1.csv,2,Jim,9876,2014-08-14,smith
1.csv,3,Jim,9876,2014-08-14,williams
1.csv,4,Jim,9876,not_a_date,jones
1.csv,5,Jim,9876,2014-08-14,dean
1.csv,6,Jim,9876,2014-08-14,Ruzyck
Desired output:
Row#5,4.csv,4,Jim,9876,not_a_date,jones (this is an erroneous row)
The condition I have chosen is print to output if anything in the date field is not a date.
As you can see, my desired output contains the line number where the error occurred, along with the data itself.
After I have my output that shows the lines within each file that are in error, I want to grab that line from the untouched original CSV file to redo (both modified and original files contain the same amount of rows). After I have a file of these redone rows, I can omit and clean up where needed to prevent interruption of an import.
Folder structure will contain:
Modified: 4.txt
Original: 4.csv
I have something started here, written in Perl, which by the logic will at least return the rows I need. However I believe my syntax is a little off and I do not know how to plug in the other subroutines.
Code:
$count = 1;
while (<>) {
unless ($F[4] =~ /\d+[-]\d+[-]\d+/)
print "Row#" . $count++ . "," . "$_";
}
The code above is supposed to give me my erroneous rows, but to be able to extract them from the originals is beyond me. The above code also contains some syntax errors.
This will do as you ask.
Please be certain that none of the fields in the data can ever contain a comma , otherwise you will need to use Text::CSV to process it instead of just a simple split.
use strict;
use warnings;
use 5.010;
use autodie;
open my $fh, '<', 'example.csv';
<$fh>; # Skip header
while (<$fh>) {
my #fields = split /,/;
if( $fields[4] !~ /^\d{4}-\d{2}-\d{2}$/ ) {
print "Row#$.,$_";
}
}
output
Row#5,4.csv,4,Jim,9876,not_a_date,jones
Update
If you want to process a number of files then you need this instead.
The close ARGV at the end of the loop is there so that the line counter $. is reset to
1 at the start of each file. Without it it just continues from 1 upwards across all the files.
You would run this like
rob#Samurai-U:~$ perl findbad.pl *.csv
or you could list the files individually, separated by spaces.
For the test I have created files 1.csv and 2.csv which are identical to your example data except that the first field of each line is the name of the file containing the data.
You may not want the line in the output that announces each file name, in which case you should replace the entire first if block with just next if $. == 1.
use strict;
use warnings;
#ARGV = map { glob qq{"$_"} } #ARGV; # For Windows
while (<>) {
if ($. == 1) {
print "\n\nFile: $ARGV\n\n";
next;
}
my #fields = split /,/;
unless ( $fields[4] =~ /^\d{4}-\d{2}-\d{2}$/ ) {
printf "Row#%d,%s", $., $_;
}
close ARGV if eof ARGV;
}
output
File: 1.csv
Row#5,1.csv,4,Jim,9876,not_a_date,jones
File: 2.csv
Row#5,2.csv,4,Jim,9876,not_a_date,jones
syntax error at bioinfo2.pl line 24, near ");"
syntax error at bioinfo2.pl line 26, near "}"
Execution of bioinfo2.pl aborted due to compilation errors.
print "Enter file name......\n\n";
chomp($samplefile = <STDIN>);
open(INFILE,"$samplefile") or die "Could not open $samplefile";
#residue_name= ();
#residue_count= ();
while($newline = <INFILE>)
{
if ($newline =~ /^ATOM/)
{
chomp $newline;
#columns = split //, $newline;
$res = join '', $columns[17], $columns[18], $columns[19];
splice #columns,0;
$flag=0
for ($i = 0; $i<scalar(#residue_name); $i++;)
{
if (#residue_name[i] == $res)
{
#residue_count[i] = #residue_count[i] + 1;
$flag=1;
}
}
if($flag==0)
{
push(#residue_name, $res);
}
for ($i = 0; $i<scalar(#residue_name); $i++)
{
print (#residue_name[i], "-------", #residue_count[i], "\n");
}
}
}
It might be advisable to use strict; use warnings. That forces you to declare your variables (you can do so with my), and rules out many possible errors.
Here are a few things that I noticed:
In Perl5 v10 and later, you can use the say function (use 5.010 or use feature 'say'). This works like print but adds a newline at the end.
Never use the two-arg form of open. This opens some security issues. Provide an explicit open mode. Also, you can use scalars as filehandles; this provides nice features like auto-closing of files.
open my $INFILE, '<', $samplefile or die "Can't open $samplefile: $!";
The $! variable contains the reason why the open failed.
If you want to retrieve a list of elements from an array, you can use a slice (multiple subscripts):
my $res = join '', #columns[17 .. 19]; # also, range operator ".."
Note that the sigil is now an #, because we take multiple elems.
The splice #columns, 0 is a fancy way of saying “delete all elements from the array, and return them”. This is not neccessary (you don't read from that variable later). If you use lexical variables (declared with my), then each iteration of the while loop will receive a new variable. If you really want to remove the contents, you can undef #columns. This should be more efficient.
Actual error: You require a semicolon after $flag = 0 to terminate the statement before you can begin a loop.
Actual error: A C-style for-loop contains three expressions contained in parens. Your last semicolon divides them into 4 expressions, this is an error. Simply remove it, or look at my next tip:
C-style loops (for (foo; bar; baz) {}) are painful and error-prone. If you only iterate over a range (e.g. of indices), then you can use the range operator:
for my $i (0 .. $#residue_name) { ... }
The $# sigil gives the last index of an array.
When subscripting arrays (accessing array elements), then you have to include the sigil of the index:
$residue_name[$i]
Note that the sigil of the array is $, because we access only one element.
The pattern $var = $var + 1 can be shortened to $var++. This uses the increment operator.
The $flag == 0 could be abbreviated to !$flag, as all numbers except zero are considered true.
Here is a reimplementation of the script. It takes the filename as a command line argument; this is more flexible than prompting the user.
#!/usr/bin/perl
use strict; use warnings; use 5.010;
my $filename = $ARGV[0]; # #ARGV holds the command line args
open my $fh, "<", $filename or die "Can't open $filename: $!";
my #residue_name;
my #residue_count;
while(<$fh>) { # read into "$_" special variable
next unless /^ATOM/; # start a new iteration if regex doesn't match
my $number = join "", (split //)[17 .. 19]; # who needs temp variables?
my $push_number = 1; # self-documenting variable names
for my $i (0 .. $#residue_name) {
if ($residue_name[$i] == $number) {
$residue_count[$i]++;
$push_number = 0;
}
}
push #residue_name, $number if $push_number;
# are you sure you want to print this after every input line?
# I'd rather put this outside the loop.
for my $i (0 .. $#residue_name) {
say $residue_name[$i], ("-" x 7), $residue_count[$i]; # "x" repetition operator
}
}
And here is an implementation that may be faster for large input files: We use hashes (lookup tables), instead of looping through arrays:
#!/usr/bin/perl
use strict; use warnings; use 5.010;
my $filename = $ARGV[0]; # #ARGV holds the command line args
open my $fh, "<", $filename or die "Can't open $filename: $!";
my %count_residue; # this hash maps the numbers to counts
# automatically guarantees that every number has one count only
while(<$fh>) { # read into "$_" special variable
next unless /^ATOM/; # start a new iteration if regex doesn't match
my $number = join "", (split //)[17 .. 19]; # who needs temp variables?
if (exists $count_residue{$number}) {
# if we already have an entry for that number, we increment:
$count_residue{$number}++;
} else {
# We add the entry, and initialize to zero
$count_residue{$number} = 0;
}
# The above if/else initializes new numbers (seen once) to zero.
# If you want to count starting with one, replace the whole if/else by
# $count_residue{$number}++;
# print out all registered residues in numerically ascending order.
# If you want to sort them by their count, descending, then use
# sort { $count_residue{$b} <=> $count_residue{$a} } ...
for my $num (sort {$a <=> $b} keys %count_residue) {
say $num, ("-" x 7), $count_residue{$num};
}
}
It took me a while to chance down all the various errors. As others have said, use use warnings; and use strict;
Rule #1: Whenever you see syntax error pointing to a perfectly good line, you should always see if the line before is missing a semicolon. You forgot the semicolon after $flag=0.
In order to track down all the issues, I've rewritten your code into a more modern syntax:
#! /usr/bin/env perl
use strict;
use warnings;
use autodie;
print "Enter file name......\n\n";
chomp (my $samplefile = <STDIN>);
open my $input_file, '<:crlf', $samplefile;
my #residue_name;
my #residue_count;
while ( my $newline = <$input_file> ) {
chomp $newline;
next if $newline !~ /^ATOM/; #Eliminates the internal `if`
my #columns = split //, $newline;
my $res = join '', $columns[17], $columns[18], $columns[19];
my $flag = 0;
for my $i (0..$#residue_name) {
if ( $residue_name[$i] == $res ) {
$residue_count[$i]++;
$flag = 1;
}
}
if ( $flag == 0 ) {
push #residue_name, $res;
}
for my $i (0..$#residue_name) {
print "$residue_name[$i] ------- $residue_count[$i]\n";
}
}
close $input_file;
Here's a list of changes:
Lines 2 & 3: Always use use strict; and use warnings;. These will help you track down about 90% of your program errors.
Line 4: Use use autodie;. This will eliminate the need for checking whether a file opened or not.
Line 7 (and others): Using use strict; requires you to predeclare variables. Thus, you'll see my whenever a variable is first used.
Line 8: Use the three parameter open and use local variables for file handles instead of globs (i.e. $file_handle vs. FILE_HANDLE). The main reasons is that local variables are easier to pass into subroutines than globs.
Lines 9 & 10: No need to initialize the arrays, just declare them is enough.
Line 13: Always chomp as soon as you read in.
Line 14: Doing this eliminates an entire inner if statement that's embraces your entire while loop. Code blocks (such as if, while, and for) get hard to figure out when they get too long and too many embedded inside each other. Using next in this way allows me to eliminate the if block.
Line 17: Here's where you missed the semicolon which gave you your first syntax error. The main thing is I eliminated the very confusing splice command. If you want to zero out your array, you could have simply said #columns = (); which is much clearer. However, since #columns is now in scope only in the while loop, I no longer have to blank it out since it will be redefined for each line of your file.
Line 18: This is a much cleaner way of looping through all lines of your array. Note that $#residue_name gives you the last index of $#residue_name while scalar #resudue_name gives you the number of elements. This is a very important distinction! If I have an #array = (0, 1, 2, 3, 4), $#array will be 4, but scalar #array will be 5. Using the C style for loop can be a bit confusing when doing this. Should you use > or >=? Using (0..$#residue) name is obvious and eliminate the chance of errors which included the extra semi-colon inside your C style for statement. Because of the chance of errors and the complexity of the syntax, The developers who created Python have decided not allow for C style for loops.
Line 19 (and others): Using warnings pointed out that you did #residue_name[i] and it had several issues. First of all, you should use $residue_name[...] when indexing an array, and second of all, i is not an integer. You meant $i. Thus #residue_name[i] becomes $residue_name[$i].
Line 20: If you're incrementing a variable, use $foo++; or $foo += 1; and not $foo = $foo + 1;. The first two make it easier to see that you're incrementing a variable and not recalculating it's value.
Line 29: One of the great features of Perl is that variables can be interpolated inside quotes. You can put everything inside a single set of quotes. By the way, you should use . and not , if you do break up a print statement into multiple pieces. The , is a list operation. This means that what you print out is dependent upon the value of $,. The $, is a Perl variable that says what to print out between each item of a list when you interpolate a list into a string.
Please don't take this as criticism of your coding abilities. Many Perl books that teach Perl, and many course that teach Perl seem to teach Perl as it was back in the Perl 3.0 days. When I first learned Perl, it was at Perl 3.0, and much of my syntax would have looked like yours. However, Perl 5.x has been out for quite a while and contains many features that made programming easier and cleaner to read.
It took me a while to get out of Perl 3.0 habits and into Perl 4.0 and later Perl 5.0 habits. You learn by looking at what others do, and asking questions on forums like Stack Overflow.
I still can't say your code will work. I don't have your input, so I can't test it against that. However, by using this code as the basis of your program, debugging these errors should be pretty easy.
I have a result of an sql query.it returns some 10 rows like below:
if i do the below in my perl script.
print $result
it gives me the output :
key value
----------- ------------------------------
1428116300 0003000
560779655 0003001
173413463 0003002
315642 0003003
1164414857 0003004
429589116 0003005
i just want to acheive that the first two lines to be deleted. and store the rest of each line in an array.
could any body please tell how do i achive this?
With something like :
my #lines = split /\n/, $result;
splice #lines,0,2;
Explanations :
split /\n/, $result is cutting your variable into an array of lines.
grep /^[\s\d]+$/ is filtering this array, and only keeps the elements that are a single line of spaces or digits (thus removing the first two lines)
Data-independent, little roundabout way: If you print $result out in a file, you can
use Tie::File;
tie #lines, Tie::File, $file or die "can't update $file: $!";
delete $lines[1];
delete $lines[2];
(untested)
I want to add a line to the text file in perl which has data in a sorted form. I have seen examples which show how to append data at the end of the file, but since I want the data in a sorted format.
Please guide me how can it be done.
Basically from what I have tried so far :
(I open a file, grep its content to see if the line which I want to add to the file already exists. If it does than exit else add it to the file (such that the data remains in a sorted format)
open(my $FH, $file) or die "Failed to open file $file \n";
#file_data = <$FH>;
close($FH);
my $line = grep (/$string1/, #file_data);
if($line) {
print "Found\n";
exit(1);
}
else
{
#add the line to the file
print "Not found!\n";
}
Here's an approach using Tie::File so that you can easily treat the file as an array, and List::BinarySearch's bsearch_str_pos function to quickly find the insert point. Once you've found the insert point, you check to see if the element at that point is equal to your insert string. If it's not, splice it into the array. If it is equal, don't splice it in. And finish up with untie so that the file gets closed cleanly.
use strict;
use warnings;
use Tie::File;
use List::BinarySearch qw(bsearch_str_pos);
my $insert_string = 'Whatever!';
my $file = 'something.txt';
my #array;
tie #array, 'Tie::File', $file or die $!;
my $idx = bsearch_str_pos $insert_string, #array;
splice #array, $idx, 0, $insert_string
if $array[$idx] ne $insert_string;
untie #array;
The bsearch_str_pos function from List::BinarySearch is an adaptation of a binary search implementation from Mastering Algorithms with Perl. Its convenient characteristic is that if the search string isn't found, it returns the index point where it could be inserted while maintaining the sort order.
Since you have to read the contents of the text file anyway, how about a different approach?
Read the lines in the file one-by-one, comparing against your target string. If you read a line equal to the target string, then you don't have to do anything.
Otherwise, you eventually read a line 'greater' than your current line according to your sort criteria, or you hit the end of the file. In the former case, you just insert the string at that position, and then copy the rest of the lines. In the latter case, you append the string to the end.
If you don't want to do it that way, you can do a binary search in #file_data to find the spot to add the line without having to examine all of the entries, then insert it into the array before outputting the array to the file.
Here's a simple version that reads from stdin (or filename(s) specified on command line) and appends 'string to append' to the output if it's not found in the input. Outuput is printed on stdout.
#! /usr/bin/perl
$found = 0;
$append='string to append';
while(<>) {
$found = 1 if (m/$append/o);
print
}
print "$append\n" unless ($found);;
Modifying it to edit a file in-place (with perl -i) and taking the append string from the command line would be quite simple.
A 'simple' one-liner to insert a line without using any module could be:
perl -ni -le '$insert="lemon"; $eq=($insert cmp $_); if ($eq == 0){$found++}elsif($eq==-1 && !$found){print$insert} print'
giver a list.txt whose context is:
ananas
apple
banana
pear
the output is:
ananas
apple
banana
lemon
pear
{
local ($^I, #ARGV) = ("", $file); # Enable in-place editing of $file
while (<>) {
# If we found the line exactly, bail out without printing it twice
last if $_ eq $insert;
# If we found the place where the line should be, insert it
if ($_ gt $insert) {
print $insert;
print;
last;
}
print;
}
# We've passed the insertion point, now output the rest of the file
print while <>;
}
Essentially the same answer as pavel's, except with a lot of readability added. Note that $insert should already contain a trailing newline.
Hello everyone I'm a beginner in perl and I'm facing some problems as I want to put my strings starting from AA to \ in to an array and want to save it. There are about 2000-3000 strings in a txt file starting from same initials i.e., AA to / I'm doing it by this way plz correct me if I'm wrong.
Input File
AA c0001
BB afsfjgfjgjgjflffbg
CC table
DD hhhfsegsksgk
EB jksgksjs
\
AA e0002
BB rejwkghewhgsejkhrj
CC chair
DD egrhjrhojohkhkhrkfs
VB rkgjehkrkhkh;r
\
Source code
$flag = 0
while ($line = <ifh>)
{
if ( $line = m//\/g)
{
$flag = 1;
}
while ( $flag != 0)
{
for ($i = 0; $i <= 10000; $i++)
{ # Missing brace added by editor
$array[$i] = $line;
} # Missing brace added by editor
}
} # Missing close brace added by editor; position guessed!
print $ofh, $line;
close $ofh;
Welcome to StackOverflow.
There are multiple issues with your code. First, please post compilable Perl; I had to add three braces to give it the remotest chance of compiling, and I had to guess where one of them went (and there's a moderate chance it should be on the other side of the print statement from where I put it).
Next, experts have:
use warnings;
use strict;
at the top of their scripts because they know they will miss things if they don't. As a learner, it is crucial for you to do the same; it will prevent you making errors.
With those in place, you have to declare your variables as you use them.
Next, remember to indent your code. Doing so makes it easier to comprehend. Perl can be incomprehensible enough at the best of times; don't make it any harder than it has to be. (You can decide where you like braces - that is open to discussion, though it is simpler to choose a style you like and stick with it, ignoring any discussion because the discussion will probably be fruitless.)
Is the EB vs VB in the data significant? It is hard to guess.
It is also not clear exactly what you are after. It might be that you're after an array of entries, one for each block in the file (where the blocks end at the line containing just a backslash), and where each entry in the array is a hash keyed by the first two letters (or first word) on the line, with the remainder of the line being the value. This is a modestly complex structure, and probably beyond what you're expected to use at this stage in your learning of Perl.
You have the line while ($line = <ifh>). This is not invalid in Perl if you opened the file the old fashioned way, but it is not the way you should be learning. You don't show how the output file handle is opened, but you do use the modern notation when trying to print to it. However, there's a bug there, too:
print $ofh, $line; # Print two values to standard output
print $ofh $line; # Print one value to $ofh
You need to look hard at your code, and think about the looping logic. I'm sure what you have is not what you need. However, I'm not sure what it is that you do need.
Simpler solution
From the comments:
I want to flag each record starting from AA to \ as record 0 till record n and want to save it in a new file with all the record numbers.
Then you probably just need:
#!/usr/bin/env perl
use strict;
use warnings;
my $recnum = 0;
while (<>)
{
chomp;
if (m/^\\$/)
{
print "$_\n";
$recnum++;
}
else
{
print "$recnum $_\n";
}
}
This reads from the files specified on the command line (or standard input if there are none), and writes the tagged output to standard output. It prefixes each line except the 'end of record' marker lines with the record number and a space. Choose your output format and file handling to suit your needs. You might argue that the chomp is counter-productive; you can certainly code the program without it.
Overly complex solution
Developed in the absence of clear direction from the questioner.
Here is one possible way to read the data, but it uses moderately advanced Perl (hash references, etc). The Data::Dumper module is also useful for printing out Perl data structures (see: perldoc Data::Dumper).
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
my #data;
my $hashref = { };
my $nrecs = 0;
while (<>)
{
chomp;
if (m/^\\$/)
{
# End of group - save to data array and start new hash
$data[$nrecs++] = $hashref;
$hashref = { };
}
else
{
m/^([A-Z]+)\s+(.*)$/;
$hashref->{$1} = $2;
}
}
foreach my $i (0..$nrecs-1)
{
print "Record $i:\n";
foreach my $key (sort keys $data[$i])
{
print " $key = $data[$i]->{$key}\n";
}
}
print Data::Dumper->Dump([ \#data ], [ '#data' ]);
Sample output for example input:
Record 0:
AA = c0001
BB = afsfjgfjgjgjflffbg
CC = table
DD = hhhfsegsksgk
EB = jksgksjs
Record 1:
AA = e0002
BB = rejwkghewhgsejkhrj
CC = chair
DD = egrhjrhojohkhkhrkfs
VB = rkgjehkrkhkh;r
$#data = [
{
'EB' => 'jksgksjs',
'CC' => 'table',
'AA' => 'c0001',
'BB' => 'afsfjgfjgjgjflffbg',
'DD' => 'hhhfsegsksgk'
},
{
'CC' => 'chair',
'AA' => 'e0002',
'VB' => 'rkgjehkrkhkh;r',
'BB' => 'rejwkghewhgsejkhrj',
'DD' => 'egrhjrhojohkhkhrkfs'
}
];
Note that this data structure is not optimized for searching except by record number. If you need to search the data in some other way, then you need to organize it differently. (And don't hand this code in as your answer without understanding it all - it is subtle. It also does no error checking; beware faulty data.)
It can't be right. I can see two main issues with your while-loop.
Once you enter the following loop
while ( $flag != 0)
{
...
}
you'll never break out because you do not reset the flag whenever you find an break-line. You'll have to parse you input and exit the loop if necessary.
And second you never read any input within this loop and thus process the same $line over and over again.
You should not put the loop inside your code but instead you can use the following pattern (pseudo-code)
if flag != 0
append item to array
else
save array to file
start with new array
end
I believe what you want is to split the files content at \ though it's not too clear.
To achieve this you can slurp the file into a variable by setting the input record separator, then split the content.
To find out about Perl's special variables related to filehandlers read perlvar
#!perl
use strict;
use warnings;
my $content;
{
open my $fh, '<', 'test.txt';
local $/; # slurp mode
$content = <$fh>;
close $fh;
}
my #blocks = split /\\/, $content;
Make sure to localize modifications of Perl's special variables to not interfere with different parts of your program.
If you want to keep the separator you could set $/ to \ directly and skip split.
#!perl
use strict;
use warnings;
my #blocks;
{
open my $fh, '<', 'test.txt';
local $/ = '\\'; # seperate at \
#blocks = <$fh>;
close $fh;
}
Here's a way to read your data into an array. As I said in a comment, "saving" this data to a file is pointless, unless you change it. Because if I were to print the #data array below to a file, it would look exactly like the input file.
So, you need to tell us what it is you want to accomplish before we can give you an answer about how to do it.
This script follows these rules (exactly):
Find a line that begins with "AA",
and save that into $line
Concatenate every new line from the
file into $line
When you find a line that begins with
a backslash \, stop concatenating
lines and save $line into #data.
Then, find the next line that begins
with "AA" and start the loop over.
These matching regexes are pretty loose, as they will match AAARGH and \bonkers as well. If you need them stricter, you can try /^\\$/ and /^AA$/, but then you need to watch out for whitespace at the beginning and end of line. So perhaps /^\s*\\\s*$/ and /^\s*AA\s*$/ instead.
The code:
use warnings;
use strict;
my $line="";
my #data;
while (<DATA>) {
if (/^AA/) {
$line = $_;
while (<DATA>) {
$line .= $_;
last if /^\\/;
}
}
push #data, $line;
}
use Data::Dumper;
print Dumper \#data;
__DATA__
AA c0001
BB afsfjgfjgjgjflffbg
CC table
DD hhhfsegsksgk
EB jksgksjs
\
AA e0002
BB rejwkghewhgsejkhrj
CC chair
DD egrhjrhojohkhkhrkfs
VB rkgjehkrkhkh;r
\