Using of typedef struct

Question

I want to know if there is any difference in performance, declaration, etc.

I have a file that called features.h, and it has a struct definition:

typedef struct feat_record
{
 ...
 ...
} Feature;

i want to use it in another file in a method, in the other file .h file I include features.h. And my question is, if there is a difference between declaring the method in the other file .h like this:

void myMethod(Feature *f);

or like this:

void myMethod (struct feat_record *f);

Thanks

Answer 1

This is only coding style and there is no other difference than subjective, personal preference.

The typedef version is often encouraged for programs that are in the borderland between C and C++, since it makes the style consistent with C++ types (in C++ the struct keyword is superfluous when declaring objects of a struct).

The struct tag version is mainly encouraged by the Linux camp and enforced by the Linux kernel code style guide (which does not provide much of a rationale beyond subjective opinions).

There is no obvious right or wrong, just pick the style you like and stick to it consistently.

Answer 2

The difference is that the typedef declaration of Feature (which may or may not include the definition of feat_record ) must precede the function declaration using it, whereas

void myMethod (struct feat_record *f);

stands on its own as an interface declaration; it does not depend on a preceding typedef or other declaration.

Nevertheless, it is better to declare struct feat_record; first, if only to silence an inevitable compiler warning. And such a declaration is required before the function declaration in the file that implements myMethod .

Ultimately, the difference is style, namely verboseness: you should decide whether you want to refer to all structs as struct in your program. It means more typing, but serves as a reminder to initialize things. (Or, if you prefer, a metadata tag for things that must be handled as a struct .)

As for the compiled program, there is no conceivable difference.