C/C++之联合体，枚举，自定义类型

联合体

#include<stdio.h>#include<stdlib.h>  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<stdio.h>#include<stdlib.h>  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<stdio.h>#include<stdlib.h>  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