Re: Origins of == in C

Brendan Gowing <Brendan.Gowing@cs.tcd.ie> writes:


> However, I think that a more intrinsic problem raised by C's "=" and
> "==" is the fact that C grammar treats both as operators in an
> expression. If this were not the case and "=" was constrained to use
> in a statement, then C compilers could spot a lot of the problems that
> you are encountering.


Our moderator writes:


> [Wizard C, the predecessor of Turbo C, had an optional warning whenever
> the top-level operator in an if or while was = and it was quite useful.
> Being a lazy typist, I took to writing if(!!(a = b)) { ... -John]


I'm surprised that noone has mentioned the solution of GCC, which I
think is better than the suggestions I've seen here.


"gcc -Wall" or "gcc -Wparentheses" warns if you use


if (a = b) { ... }


and you can shut it up by using


if ((a = b)) { ... }


which IMHO looks a lot less ugly than !!(a = b).


Bas.
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