What _did_ the C operators /\ and \/ do?

Question

Anyone can "declare" ones own operators in C.... that is if one is a C compiler guru and has the source code to the C compiler! ;-)

Further questions to puzzle:

5. How are these operations done in C99? gcc? ...
6. And why were /\ & \/ dropped?
7. Which types were the /\ and \/ operators valid for?

Googling for "/\ \/" naturally returns nothing. Wikipedia has a page for neither /\ nor \/. But I have spotted form similar operators are built into the XML character entities!

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Source added: I found the offending example in the PDP's cc source file "c00.c":

/*  * Return the next symbol from the input.  * peeksym is a pushed-back symbol, peekc is a pushed-back  * character (after peeksym).  * mosflg means that the next symbol, if an identifier,  * is a member of structure or a structure tag or an enum tag  */ symbol() { ...  case BSLASH:   if (subseq('/', 0, 1))    return(MAX);   goto unkn;   case DIVIDE:   if (subseq('\\', 0, 1))    return(MIN);   if (subseq('*',1,0))    return(DIVIDE); ... } 

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Actual Implementations: The /\ and \/ operators date back as far as Sixth Edition Unix 1975 (so far). Examples: Unix V6(1975), Unix V7(1979) and more currently BSD 2.11(1992-2008)

Answer 1

Neither /\ nor / are defined as operators in the ISO C89 standard, and I don't think they were ever defined in any earlier version. And they are definitely not defined in C99 as far as I know.

Here's a draft of the ANSI C89 standard, for reference: http://flash-gordon.me.uk/ansi.c.txt

(You are likely a victim of some weird arcane preprocessor magic)

Answer 2

\/ looks like sup and /\ looks like inf. They could also be ∨ and ∧, respectively.

I don't remember ever seeing these in K&R 2nd edition or any other C book.