C/C++之联合体，枚举，自定义类型

联合体

#include
#include


  main(){


    //定义一个联合体
    union  {int i;short s;char c;} tt; 
   tt.i = 3; 

   printf("%d\n",tt.i);
     printf("联合体的长度%d\n",sizeof(tt));//为最长的int 4 
    system("pause");

    }

枚举

#include
#include


  main(){

   enum WeekDay{
        Monday = 10,TuesDay,Wednesday,Thursday,Friday,Saturday,Sunday
        }; 
  enum WeekDay day = Sunday;


     printf("枚举%d\n",day); //结果是6，如果Monday = 10 ，结果是16 
    system("pause");

    }

自定义类型

#include
#include

  typedef int tni; 

  main(){
   tni i = 2;
     printf("自定义类型tni%d\n",i);
    system("pause");

    }

java–>jdk–>include–>jni.h文件