Is typedef ever required in C?

Question

Typedef is very useful for portable names, tag names (typedef struct foo Foo;) and keeping complicated (function) declarations readable (typedef int (*cmpfunc

Answer 1

Thanks all for your answers. I looked some more myself and found this in C99, J.2 Undefined behaviour:

The behavior is undefined in the following circumstances: [...]

• The type parameter to the va_arg macro is not such that a pointer to an object of that type can be obtained simply by postfixing a * (7.15.1.1).

So when you want to pass/extract complicated derived types to va_arg such as int (*)[] you need to typedef this type to something for which this is possible (updated/corrected):

typedef int (*intarrptr)[4];
intarrptr x = va_arg(ap, intarrptr);

Since it is difficult to find and actual useful case for this one might conclude that it is not a strong argument for the necessity of typedef.