static - Declaration and Definition of variables in c

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I understand the terms declaration and
definition as
below.

Declaration:
This is just a heads up to the compiler that a variable of specified
"name" and "type" exists in
the code. So that it can be defined/assigned at later point of
time

Definition:
This is the process where an instance of the type is created by allocating a suitable
space of memory.

int var;
            //Declaration and Definition-Agreed!!!
extern int var; //Declaration only
            ?
static int var; //Declaration only
            ?

My mind refuses to
agree the second and third ones as declaration only
statements. Because in many references I see, "extern and static variables
are automatically initialized to zero upon memory allocation". And as you
see in following code.

#include
            

int main()
{
 static int
            i;
 printf("%d\n",i);
 return
            0;
}

The
output is 0. So Here it looks like the static int i; is
declaration,definition and auto initialization statement. So please add your
justification for this

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class="normal">Answer

Objects with static storage
duration are initialized by zero in
C.

static int a; // initialized by
            zero
int b; // file-scope, static storage duration, initialized by
            zero

int main(void)
{
 int c; // automatic
            storage duration, indeterminate value
 static int d; // initialized by
            zero
}

a,
c and d are declarations and
definitions of
objects.

b is a
declaration and a definition because there is no other file-scope occurrence of
b until the end of the translation unit. Before the end of the
translation unit, the declaration is a tentative
definition.