🚀 go-pugleaf

Here's an interesting MS FORTRAN 77 compiler V2.2 behavior that confused
(might one say abused?) an amazing number of my students this semester:

 > 00001        program STRTST
 > 00002        character*14 STR1, STR2
 > 00003
 > 00004        STR1 = 'abcdefghijklmnopqr'
 > 00005  C                                   Now for erroneous use of STR1:
 > 00006        STR2 = STR1 (2,5)
 > 00007  C                                   Some filler lines:
 > 00008        print *, 'STR1 = "', STR1, '"'
 > 00009        print *, 'STR2 = "', STR2, '"'
 > 00010  C                                   Now for proper use of STR1:
 > 00011        STR2 = STR1 (2:5)
 > 
 > *****  error in line 00011 [TR1 (2]: too many left parantheses
 > 
 > 00012
 > 00013        stop
 > 00014        end
 > 
 > *****  1 error

Note that improper use (as a 2-D array) of the STR1 string variable is
not flagged, and the compiler subsequently forgets that STR1 is a string.
This is especially hard on beginning FORTRAN students since the point of
detection may be many lines beyond of the point of the error.

(BTW, would some Microsoft person on the net be so kind as to tell me
 what "parantheses" are?  I think even one of these would be too many. :-)

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Another one "good for a grin" is the beginner's DO-loop running from 1
to "10000" (yes, many beginners make this mistake):

 > do 99 I = 1, 10,000
 >    ...

This one actually crashes the compiler and often takes the system out too.

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Speaking of crashing the system ...

One of my TAs is working on a "lint" program for FORTRAN to give students
a means of finding mis-matched actual and formal argument lists.  Since
most of these mismatches cause MSF runtime crashes (i.e. system dies too),
and some even cause compile-time crashes (ditto), such a program would be
invaluable to the students.  If anyone else is interested (or has already
written such a beast!) please contact me by email.

        David McNabb

        Department of Computer Science
        University of Illinois at Urbana-Champaign
        USENET:	...!{cmcl2,seismo,ihnp4}!uiucdcs!mcnabb
        ARPA:	mcnabb@a.cs.uiuc.edu