常數定義

1. 使用前處理定義

   #include <stdio.h>
   
   #define LENGTH 10   
   #define WIDTH  5
   #define NEWLINE '\n'
   
   int main()
   {
   
      int area;  
     
      area = LENGTH * WIDTH;
      printf("value of area : %d", area);
      printf("%c", NEWLINE);
   
      return 0;
   }
   

2. 使用關鍵字 const

   #include <stdio.h>
   
   int main()
   {
      const int  LENGTH = 10;
      const int  WIDTH  = 5;
      const char NEWLINE = '\n';
      int area;  
      
      area = LENGTH * WIDTH;
      printf("value of area : %d", area);
      printf("%c", NEWLINE);
   
      return 0;
   }