No. It is very standard and normal C style. Your example is a bad one, because it should just be a for loop, but in general there's nothing wrong with
if ((a = f()) != NULL)
    ...
for example (or with while).
No. It is very standard and normal C style. Your example is a bad one, because it should just be a for loop, but in general there's nothing wrong with
if ((a = f()) != NULL)
    ...
for example (or with while).