Greetings everyone, I'm working on a Summer project and I have a little problem with my PERL code. I'm supposed to print all "ATOM" lines of a Protein PDB file and the parts I am supposed to print should not contain Hydrogen "H" atoms in the atom part, which is in between the columns 13-16. I think I got the regex for it right but it prints all the ATOM lines including ones with hydrogen atoms so I definitely got the syntax wrong. Any ideas on how to fix it ? Thanks. This is the code for printing -to a file- the ATOM lines that don't have Hydrogen 
while($text =~ m/((ATOM)(\s{1,})(\d{1,})(\s{1,})(\w+)(\s{1,})[A-Z]{1,}
+(\s{1,})[A-Z]{1,}(\s{1,})(\d{1,})(\s{1,})(\W+\d+.\d+)(\s{1,})(\W+\d+.
+\d+)(\s{1,})(\W+\d+.\d+)(\s{1,})(\W+\d+.\d+)(\s{1,})(\d+.\d+)(\s+)([A
+-Z]{1}))/gi)
{

    
    print MYFILE "$1";
    print MYFILE "\n";

}

[download]
And this is for printing HETATM lines that don't have HOH string and it has the same syntax with the one above, yet this works while the one at the top doesn't.. 
while($text =~ m/((ATOM)(\s{1,})(\d{1,})(\s{1,})(\w+)(\s{1,})[A-Z]{1,}
+(\s{1,})[A-Z]{1,}(\s{1,})(\d{1,})(\s{1,})(\W+\d+.\d+)(\s{1,})(\W+\d+.
+\d+)(\s{1,})(\W+\d+.\d+)(\s{1,})(\W+\d+.\d+)(\s{1,})(\d+.\d+)(\s+)([A
+-Z]{1}))/gi)
{

    
    print MYFILE "$1";
    print MYFILE "\n";

}

[download]

In reply to Help for a regex problem ? by hellworld

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