what exactly is tags in C?

[s.subbarayan]

Dear all,
With respect to structures whats actually "tags" in C?Is is that
tags are mainly used for self referential structures and what else are
the purpose of using tags in C?How does a tag differ from typedef with
respect to structures in C?
Expecting all your replys and advanced thanks for the same,
Regards,
s.subbarayan

 

[Richard Bos]

With respect to structures whats actually "tags" in C?

The tag is the identifier used to refer to a struct, union or enum type.
For example, in struct rectangle { int height; int width; };, rectangle
is the tag.

Is is that tags are mainly used for self referential structures

No; they're used for any tag that you want to refer to without using
typedef.

How does a tag differ from typedef with respect to structures in C?

A typedef name is in the normal name space; if you have a typedef foo
you can't also have an int foo.

Richard