【C++】结构体/结构体数组/结构体指针/结构体嵌套/函数参数/const

一、结构体声明

struct Student
{
      //成员列表
      string name;
      int age;
      int score;
}; //s3;定义时直接声明

int main()
{
      struct Student s1;
//法一、直接赋值
      s1.name = "Apple";
      s1.age = 10;
//法二、直接声明
      struct Student s2 = {"Banana", 19, 80}; //不可跳着声明
}

二、结构体数组
//创建结构体数组

int main()
{
      struct Student stuArray[3] = 
      {
            {"Apple", 19, 80},
            {"Banana", 18, 99},
            {"Cat", 17, 70}
      }; //注意逗号，分号的位置
}

//给结构数组中赋值

int main()
{
    struct Student stuArray[3] = 
    {
        {"Apple", 19, 80},
        {"Banana", 18, 99},
        {"Cat", 17, 70}
    };
    
    stuArray[0].name = "Dog";

    cout << stuArray[0].name << stuArray[0].score <<endl;
    system("pause");
}

//遍历结构体数组：for循环

三、结构体指针

int main()
{
    struct Student stuArray[3] = 
    {
        {"Apple", 19, 80},
        {"Banana", 18, 99},
        {"Cat", 17, 70}
    };
    
    stuArray[0].name = "Dog";

    cout << stuArray[0].name << stuArray[0].score <<endl;

    //结构体指针
    Student* p = &stuArray[0]; //定义
    int a = p -> score; //访问 ->
    cout << a <<endl;
    system("pause");
}

四、结构体嵌套结构体

struct Student
{
      //成员列表
      string name;
      int age;
      int score;
}; 

struct Teacher
{
    int id;
    string name;
    int age;
    struct Student stu;
};

五、结构体作为函数参数
结构体作为函数参数有值传递和地址传递两种。

#include <iostream>
#include <stdlib.h>
using namespace std;

struct Student
{
      //成员列表
      string name;
      int age;
      int score;
}; 

//值传递
void printStudent(struct Student s)
{
    s.name = "Banana";
    cout << "name: " << s.name << "age: " << s.age << "score: " << s.score <<endl;
}

//地址传递
void printStudent2(struct Student* p)
{
    //p->name = "Banana";
    cout << "name: " << p->name << "age: " << p->age << "score: " << p->score << endl;
}

int main()
{
    struct Student s;
    s = {"Apple", 20, 89};
    printStudent(s);
    struct Student* p = &s;
    printStudent2(p);
    cout << "name: " << p->name << "age: " << p->age << "score: " << p->score << endl;
    system("pause");
}

六、结构体中使用const场景
用于防止误操作。
因为值传递浪费空间，所以一般使用地址传递。
如果函数使用了地址传递，函数内操作会改变实参值，为了防止实参被乱修改，使用const。


用于设置只能读不能写。