Re: Language design after Algol 60

From John Levine
Sent: Monday, April 16, 2018 10:56 PM


> [Perhaps he meant that it was impossible for *him* to master the language.
> It does have some odd rough edges, e.g., give or take my recollection of
> the syntax:


> DCL (A,B,C) CHAR(3);
> A = '123';
> B = '456';
> C = A+B;


> What does C contain? Answer: three spaces. -John]


No. IBM's PL/I for Windows compiler produces two diagnostics:


1: at compilation time, at line 6 [your line 4]:


(6:1) : IBM1211I W Source in string assignment is longer than the target C.


2. At execution time, a fatal error at the assignment C = A+B :


IBM0441I ONCODE=0150 The STRINGSIZE condition was raised.
      At offset +0000016B in procedure with entry L


Character variables were not really intended for doing decimal arithmetic,
though conversions from character to decimal are more-or-less common.


I'm not sure whether a compiler warning message would have been
produced in the 1960s with the PL/I F-compiler,
but am fairly certain that there would have been no run-time error.
[I got the three spaces in PL/I F. I dimly recall that if I turned on optimization,
it'd do constant substitution and just move the three spaces into C. Nice to hear
that they warn you off this design error now. -John]

Return to the comp.compilers page.
Search the comp.compilers archives again.