What are the differences between these two typedef styles in C?

Question

I\'m curious what the difference here is when typedefing an enum or struct. Is there any difference semantically between these two blocks?

This:

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Answer 1

Adding to user207442's comment, it's possible for a source code module to declare variables of type "struct foo *" without ever having a definition for the struct. Such a module will not be able to dereference such pointers, but may pass them to and from other modules.

For example, one could have a header file define a type "USERCONSOLE" using "typedef struct _USERCONSOLE *USERCONSOLE;". Code that #include's that header file could have variables of type USERCONSOLE, and pass such variables to/from modules that know what a _USERCONSOLE really is, without the header file having to expose the actual definition of the structure.