////  main.m//  结构体作为对象的属性#import 
     
      typedef struct {    int year;    int month;    int day;} Date;@interface Student : NSObject{    @public    NSString *_name;    // struct Date birthday;    Date _birthday;}- (void)say;@end@implementation Student- (void)say{    NSLog(@"name = %@; year = %i, month = %i, day = %i", _name, _birthday.year, _birthday.month, _birthday.day);}@endint main(int argc, const char * argv[]) {    Student *stu = [Student new];//结构体里面的值都是0    stu->_name = @"lnj";    // 1.结构体只能在定义的时候初始化    // 2.系统并不清楚它是数组还是结构体        //初始化结构体属性    //方法一:强制转换    stu->_birthday = (Date){
   1986, 1, 15};//大括号有可能是数组，        //方法二:定义一个新的结构体,给d赋值,将d赋值给_birthday    Date d = {
   1986, 1, 15};    stu->_birthday = d;        //方法三:分别赋值    stu->_birthday.year = 1986;    stu->_birthday.month = 1;    stu->_birthday.day = 15;        // 3.让学生说出自己的姓名和生日    [stu say];                Date d1  = {
   1999, 1, 5};    Date d2;    d2 = d1; // 本质是将d1所有的属性的值都拷贝了一份赋值给d;不是传递地址        d2.year = 2000;    printf("d1 = year = %i\n", d1.year);//1999    printf("d2 = year = %i\n", d2.year);//2000    return 0;}