Are `typedef` and `struct` inside of a function standard in C?

Question

I used some code like this:

void A()
{
    typedef struct B B;
    struct B
    {

    };

    B b;
};

typedef and struct definition inside a function. It compiled with Clang, but I want to know (1) whether they are part of standard or not. And about (2) whether they are limited to be recognized in function scope only.

Answer 1

Yes, the standard allows this, and yes, the name you create this way is only visible inside the function (i.e., it has local scope, just like when you define int i;, i has local scope).

It's more common, however to do it something like this:

typedef struct { 
    /* ... */ 
} B;
B b;