text: #include <stdio.h>
  
  /* static variables
   * 1. A static variable inside a function keeps its value between invocations
   * 2. A static global variable or a function is "seen" only in the files
   *    it's declared in
   */
  
  void foo() {
      int a = 10;
      static int sa = 10;
  
      a += 5;
      sa += 5;
  
      printf("a = %d, sa = %d\n", a, sa);
  }
  
  int main () {
      int i;
  
      for (i = 0; i < 10; ++i)
          foo();
  }
  