c++ 8、结构体

1、结构以定义

typedef struct 
{
     member_type1 member_name1;
     member_type2 member_name2;
     member_type3 member_name3;
      .
      .
} object_names;

示例：
typedef struct
{
     char[50] title;
     char[500] desc;
     int id;
}Book;

2、访问结构成员

成员访问运算符.访问：
结构体指针->访问：
有如下代码>>>>>>:

#include <iostream>
#include <string>
#include <stdio.h>
using namespace std;

typedef struct
{
    string title;
    string desc;
    int id;
}Book;

int main()
{
    Book book1;
    Book book2;

    // 成员运算符访问
    book1.title = "三国演义";
    book1.desc = "乱世争霸";
    book1.id = 1;

    // 指针访问
    Book *p;
    p = &book2;
    p->title = "水浒传";
    p->desc = "梁山起义";
    p->id = 2;

    cout << book1.title << endl;
    cout << book2.title << endl;
    return 0;
}

运行结果：

三国演义
水浒传

3、结构体传参

函数可以将结构体当作参数转递，也可将结构体指针当作参数进行传递。需要注意的是，当结构体作为形参参入函数时，是无法真正改变结构体内部的值的

#include <iostream>
#include <string>
#include <stdio.h>
using namespace std;
typedef struct
{
    string title;
    string desc;
    int id;
}Book;

extern void PrintBook(Book book);    // 此种传参无法改变book结构体的值
extern void PrintBook(Book *book);


int main()
{
    Book book1;
    Book book2;
    Book *p;
    p = &book2;

    book1.title = "海底两万里";
    book1.desc = "海底探险";
    book1.id = 3;

    book2.title = "钢铁是怎样炼成的";
    book2.desc = "小男孩的成长史";
    book2.id = 4;

    PrintBook(book1);
    PrintBook(p);
    return 0;
}

void PrintBook(Book book)
{
    cout << book.title << endl;
    cout << book.desc << endl;
    cout << book.id << endl;
}

void PrintBook(Book *book)
{
    cout << book->title << endl;
    cout << book->desc << endl;
    cout << book->id << endl;
}

运行结果:

海底两万里
海底探险
3
钢铁是怎样炼成的
小男孩的成长史
4