Error : Redeclaration with no linkage

Question

#include<stdio.h>
int x=13; // forcing space allocation 
int x; 
int main(){
  printf("%d\n",x); 
}

The code above compiles but the one below does not. why ?

#include<stdio.h> 
int main(){
  int x=13; // forcing space allocation 
  int x;
  printf("%d\n",x); 
}

i was told that int x ; can be interpreted by the complier as a declaration or definition depending on the context . i can see that in the first case(global one) but what happens in the second.

Answer 1

Quoting:

You can't have two global variables with the same name in C program. C might allow multiple definitions in the same file scope through the tentative definition rule, but in any case all definitions will refer to the same variable.