title: Use function pointer initialized in other source file
body: <p>I have function pointer, that is declared as follows in file 1.h</p>
  
  <pre><code>// file : 1.h
  typedef void (*my_func_ptr_T)(int , int);
  </code></pre>
  
  <p>In file 1.c I create a global instance and initialize it</p>
  
  <pre><code>// file 1.c
  my_func_ptr_T func;
  
  void callback (my_func_ptr_T _ptr) {
      func = _ptr;
  }
  </code></pre>
  
  <p>Now, how can i use this function ptr 'func' in another file say 2.c</p>
  
  <pre><code>// file 2.c 
  void do_callback() {
      //  i want to do this
      func(1,2);
  }
  </code></pre>