#include <stdio.h> // 变量声明 extern int a, b; extern int c; extern float f; int main () { /* 变量定义 */ int a, b; int c; float f; /* 初始化 */ a = 10; b = 20; c = a + b; printf("value of c : %d \n", c); f = 70.0/3.0; printf("value of f : %f \n", f); return 0; }