Re: Origins of == in C

>The distinction between = and == in C has caused me no end of
>grief. I read in the introduction to _The C Programming
>Language_ by K&R that C's ancestory is BCPL -> B -> C. BCPL used
>:= for assignment and = for comparison. Could someone point me
>to a definition of B or explain how (and why) assignment and
>comparison migrated from what I consider a much safer form to
>the current error-prone form.


I think the extent of this problem depends on what languages you have used
before - I have only ever programmed extensively in C and not greatly troubled
by == and =.


There is a useful book on the development of C - I have grabbed the
details from our catalogue.


  Author Emery, Glyn
  Title BCPL and C / Glyn Emery
  Place Oxford [Oxfordshire] Boston
  Publisher Blackwell Scientific Publications
  Publish Date 1986
  Collation 173 p. : ill ; 24 cm.
  Subjects BCPL (Computer program language)
                   C (Computer program language)
  Notes Includes index
  Bibliographic no 00451103
  Local Control no h07884
  Series (Computer science texts)
  Isn 0632016078 0632015713


Also the web site http://sf.www.lysator.liu.se/c/ has some information on the
development of BCPL->B->C. Note:
http://www.lysator.liu.se/c/chistory.ps - Dennis Ritchie on the develop-
ment of the C language.
http://www.lysator.liu.se/c/clive-on-bcpl.html - Clive Feather on BCPL
http://www.lysator.liu.se/c/alan-on-bcpl.html#bcpl-main - Alan Watson
on BCPL
http://www.lysator.liu.se/c/msb-on-b.html#main - Mark Brader on B
http://www.lysator.liu.se/c/dmr-on-or.html#main - Dennis Ritchie on
precedence of '|', '&' and '=='


I hope you may find something of use amongst these documents.


Doug
|--------------------------------------------|
| Dr Doug Chappell |
| Department of Biochemistry |
| The University of Sydney, 2006 |
| NSW AUSTRALIA |
| Phone: 61-2-692-2511 |
| Facsimile: 61-2-692-4726 |
| Email: D.Chappell@biochem.usyd.edu.au |
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