Please explain syntax rules and scope for "typedef"

Question

What are the rules? OTOH the simple case seems to imply the new type is the last thing on a line. Like here Uchar is the new type.

typedef unsigned char Uchar;

But a function pointer is completely different. Here the new type is pFunc:

typedef int (*pFunc) (int);

I can't think of any other examples offhand but I have come across some very confusing usages.

So are there rules or are people just suppose to know from experience that this is how it is done because they have seen it done this way before?

ALSO: What is the scope of a typedef.

Thanks to everyone.

Answer 1

Basically a typedef has exactly the same syntax as an object declaration except that it is prefixed with typedef and that changes the meaning so that the new identifier declares an alias for the type that the object that would have been declared had it been a normal declaration would have had.

A typedef is scoped exactly as the object declaration would have been, so it can be file scoped or local to a block or (in C++) to a namespace or class.

e.g.

Declares an int:

int a;

Declares a type that is an alias for int:

typedef int a_type;

Declares a pointer to a char:

char *p;

Declares an alias for a char *

typedef char *pChar;

Declares a function pointer:

int (*pFn)(int);

Declares an alias for the type that is 'pointer to a function taking int and returning int'.

typedef int (*pFunc)(int);

Answer 2

This is covered and answered in Chapter 6, section 6.7 "Typedef" page 146, and A8.9 "Typedef" of Appendix A page 221, of The C Programming Language, 2nd ed. by Brian W. Kernighan and Dennis M. Ritchie (K&R).

A more comprehensive answer can also be found in C: A Reference Manual, 5th ed., by Samuel P. Harbison III and Guy L. Steele Jr. in Chapter 5, Section 5.10.

These two books are taken as the two references used by C programmers, other than the international ISO (9899:1999, aka C99) standards themselves. I would strongly advocate that you get one, if not both of these references for your own use.