Wow!, Thanks, Jose-Marcio, Michael, NeonJohn, David and Tim, I am out-of-date and out-of-touch. You've taught me a lot. I didn't distinguish whether '64bit' was processor or OS. Now I know. I knew nothing of intXX_t. I did wonder whether a new long long int or an extra long int had appeared. I'm using gcc, so I'll inspect sys/types.h, and experiment. Thanks for all your trouble and informative replies. I'm sure I'll not be the only one to benefit. JJ -- View this message in context: http://gcc.1065356.n5.nabble.com/C-Integers-tp935964p936011.html Sent from the gcc - Help mailing list archive at Nabble.com.