Hi, The definition of the mpz_tstbit function is: int mpz_tstbit (mpz_t op, unsigned long int bit_index) Why not: bool mpz_tstbit (mpz_t op, unsigned long int bit_index) Why not: int mpz_tstbit (mpz_t op, mpz_t bit_index) Regards, Cpm. -- __ __ __ (o_ | |__| | | "CPM est Christian P. M____." ('< /) |__ . | . | | . cp.momon@ocmland.org ,',)