a perl regex to check whether a sequence is pure DNA or not. bonus question: what if I also need to allow IUPAC code for DNA. thx, L. -- ============================================================== Lieven Sterck, PhD Tel:+32 (0)9 3313821 Fax:+32 (0)9 3313809 VIB Department of Plant Systems Biology, UGent Bioinformatics and Evolutionary Genomics Division Technologiepark 927, B-9052 Gent, Belgium Email: lieven.sterck@psb.ugent.be Website: http://bioinformatics.psb.ugent.be -------------------------------------------------------------- Algal Genetics Group UMR 7139 CNRS-UPMC Végétaux Marins et Biomolécules (Marine Plants and Biomolecules) Station Biologique Place Georges Teissier, BP74 29682 Roscoff Cedex, France Website: http://www.sb-roscoff.fr/UMR7139/en/genetics.html ============================================================== "Facts are meaningless. You could use facts to prove anything that's even remotely true!" H. Simpson