self doubt variable scope

Question

#include <stdio.h>
 
/* global variable declaration */
int g = 20;
 
int main () {

  /* local variable declaration */
  int g ;
 
  printf ("value of g = %d\n",  g);
 
  return 0;
}

why this printing value of g is 0 instead of garbage  because g is declared which is local variable  in main function.    are variables inside main function by default global?  

Comments

It should be garbage.

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answer is 0

https://ideone.com/fork/A00bGd

Answer 1

no, by default variables inside main function is not by default global