Why these original FORTRAN quirks?
in [Fortran]
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From: Gary Scott on 22 Oct 2006 00:05 Terence wrote: > Short comment on Gary's note on:- > > >>>>It wasn't so easy in the days of 6-character name length limits. >> >>I tend to agree in that I never had much difficulty with 6 character >>names because there was considerable discipline used in the naming >>conventions we used. > > > My memory is that at least one of the earlier Fortran compilers I > worked with allowed SIX-letter variable names only in the main program. > And FIVE-letter names as variables in subroutines and functions. > Although I learned Fortran in the early sixties, I seem to think this > rule caught my attention working with IBM main-frames compilers, > Hewlett-Packard and Modcomp minicomputers (and their fortran compilers) > all at the same time in the seventies . > So maybe one of these had the quirk and I learned to play safe. So to > this day I have the fixed habit of using FIVE letters only for > variables (and fixed format). > > And surely a suffix ".f" (which I saw as advice to someone in this > forum) is equivalent to the normal ".for" to indicate a fixed-format > program to an F90 compiler ? > That wouldn't apply to some OS though that don't have a concept of a file name "suffix". -- Gary Scott mailto:garylscott(a)sbcglobal dot net Fortran Library: http://www.fortranlib.com Support the Original G95 Project: http://www.g95.org -OR- Support the GNU GFortran Project: http://gcc.gnu.org/fortran/index.html Why are there two? God only knows. If you want to do the impossible, don't hire an expert because he knows it can't be done. -- Henry Ford
From: William J. Leary Jr. on 22 Oct 2006 00:35 "Terence" <tbwright(a)cantv.net> wrote in message news:1161472385.953880.177910(a)m73g2000cwd.googlegroups.com... > My memory is that at least one of the earlier Fortran compilers > I worked with allowed SIX-letter variable names only in the main > program.And FIVE-letter names as variables in subroutines and > functions. This sounds vaguely familiar to me. I used FORTRAN (when it was still all uppercase) on DG, DEC and [[some other]] computers back in the late 70's and early 80's. One of them, I can't recall which, had some limitation like that. Specifically, some short length in the main program, and that length minus one in either subroutines or separately compiled modules. - Bill
From: glen herrmannsfeldt on 22 Oct 2006 03:38 Brian Inglis wrote: (snip on C, struct, and operators) > And what would these operators mean applied to a struct? > You need C++, but it's not intuitively obvious what those operators > would mean, so using member functions with meaningful names would be > more obvious e.g. zero_stuff, inc_stuff, add_stuff. It took Fortran many years to add array operations, yet they seem obvious once added. Initializing a whole array with as A=0 seems obvious enough, why not initialize a whole structure in a similar way? That would, of course, depend in the operation making sense, in that the structure would have to contain only elements where assigning 0 made sense. Similarly, A=B+C now seems obvious for arrays, but not structures. Again, structures containing elements where the + operator makes sense could easily have this operation added. I have previously described what PL/I will do with character variables and numeric operations. It will do those with structures containing such variables, too. I won't propose that Fortran should do that. -- glen
From: glen herrmannsfeldt on 22 Oct 2006 03:45 Gary Scott wrote: (snip) >> And surely a suffix ".f" (which I saw as advice to someone in this >> forum) is equivalent to the normal ".for" to indicate a fixed-format >> program to an F90 compiler ? > That wouldn't apply to some OS though that don't have a concept of a > file name "suffix". Older DEC OSs, later adapted by DOS, had the suffix as part of the file system. Some allowed for a six character file name and a three character extension. For VAX/VMS the shortest possible file name is .; For unix, it was convention to add a . suffix to names, but to the system . was just another character. If . was not a legal character, one could find another separator, or specify that the last character of the name was the indicating suffix. -- glen
From: glen herrmannsfeldt on 22 Oct 2006 03:56
Terence wrote: (snip) > My memory is that at least one of the earlier Fortran compilers I > worked with allowed SIX-letter variable names only in the main program. > And FIVE-letter names as variables in subroutines and functions. (snip) For the first Fortran compiler, in the manual 50 years and one week old: "The name of a function is 4 to 7 alphabetic or numeric characters, (not special characters) of which the last must be F and the first must be alphabetic. Also, the first must be X if and only if the function is to be fixed point." Also, "The name of a variable must not be the same as the name of any function used in the program after the terminal F of the function name has been removed. Also, if a subscripted variable has 4 or more characters in its name, the last of these must not be an F." Six letter names are especially convenient for 36 bit machines using a six bit character set, or that internally adopt a six bit character set for some names. -- glen |