三种定义常量的方法

1 #include 
     
       2  3 //1. 预编译 4 #define PI 3.14 5  6 int main(void) 7 { 8 //2. const关键字 9     const int LENGTH = 100;10 11 //3. 枚举类型12     enum color {13         RED,14         GREEN,15         BLUE16     };  17     printf("pi = %f\n", PI);18     printf("length = %d\n", LENGTH);19     printf("red  = %d\n", RED);20     printf("green = %d\n", GREEN);21     printf("blue  = %d\n", BLUE);22 }