形式参数

#include <stdio.h>



/* global variable declaration */

int a = 20;



int main () {



  /* local variable declaration in main function */

  int a = 10;

  int b = 20;

  int c = 0;



  printf ("value of a in main() = %d\n",  a);

  c = sum( a, b);

  printf ("value of c in main() = %d\n",  c);



  return 0;

}



/* function to add two integers */

int sum(int a, int b) {



   printf ("value of a in sum() = %d\n",  a);

   printf ("value of b in sum() = %d\n",  b);



   return a + b;

}