Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site decvax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!minow From: minow@decvax.UUCP (Martin Minow) Newsgroups: net.lang Subject: Runtime trapping of program bugs Message-ID: <19@decvax.UUCP> Date: Tue, 8-Jan-85 00:32:25 EST Article-I.D.: decvax.19 Posted: Tue Jan 8 00:32:25 1985 Date-Received: Wed, 9-Jan-85 02:44:54 EST References: <5143@rochester.UUCP> Lines: 16 Ken Yap mentioned that the VMS Fortran compiler puts constants in read-only memory so the operating system could trap subroutines that incorrectly write to their parameters. He asked if other compilers did the same. Some very old Fortran compilers initialized all variables to an "illegal" floating point constant (I think -0 was used on the 7090) to trap the fairly common error where a variable was read before it was initialized. The PDP-11 floating-point format has an "illegal float" defined for just that purpose, but I don't think it's used by any '11 language. Martin Minow decvax!minow