C++类和对象

#include <iostream>
using namespace std;
//实现一个表示学生的类
//struct Student{
class Student{
public:
    //行为:成员函数
    void eat(const string& food){
        cout << "我在吃" << food << endl;
    }
    void sleep(int hour){
        cout << "我睡了" << hour << "小时"
            << endl;
    }
    void learn(const string& course){
        cout << "我在学" << course << endl;
    }
    void who(void){
        cout << "我叫" << m_name << ",今年"
            << m_age << "岁,学号是" << m_no
            << endl;
    }
public:
    /* 私有成员不能在类的外部直接访问,但是可以
     * 提供公有的成员函数来间接访问,在函数中可
     * 以对非法数据加以限定,控制业务逻辑的合理
     * 性----封装思想*/
    void setName(const string& name){
        if(name == "二"){
            cout << "你才二" << endl;
        }
        else{
            m_name = name;
        }
    }
    void setAge(int age){
        if(age < 0){
            cout << "无效年龄" << endl;
        }
        else{
            m_age = age;
        }
    }
    void setNo(int no){
        if(no < 10000){
            cout << "无效学号" << endl;
        }
        else{
            m_no = no;
        }
    }
private:
    //属性:成员变量
    string m_name;
    int m_age;
    int m_no;
};
int main(void)
{
    //原来:定义结构体类型变量
    //现在:创建对象 或 实例化对象
    Student s;
    /*s.m_name = "张飞";
    s.m_name = "二";
    s.m_age = 28;
    s.m_no = 10086;*/
    s.setName("张翼德");
    s.setName("二");
    s.setAge(29);
    s.setAge(-2);
    s.setNo(10011);
    s.setNo(290);
    s.who();
    s.eat("拉州拉面");
    s.sleep(8);
    s.learn("C++编程");
    return 0;
}

#include <iostream>
using namespace std;
class Student{
public:
    Student(const string &name,int age,int no){
        cout << "构造函数" << endl;
        m_name = name;
        m_age = age;
        m_no = no;
    }       
    void who(void){
        cout << "我叫" << m_name << ",今年" <<
            m_age << "岁,学号是" << m_no <<
                endl;
    }
private:
    string m_name;
    int m_age;
    int m_no;
};
int main(void)
{
    //创建对象/实例化对象/构造对象
    //(...):指定构造函数需要的实参
    Student s("张飞",28,10011);
    s.who();
    //构造函数不能显式调用
    //s.Student("张三",29,10012);
    return 0;
}

#include <iostream>
using namespace std;
class A{
public:
    A(void){
        cout << "A的无参构造函数" << endl;
        m_i = 0;
    }
    A(int i){
        cout << "A的有参构造函数" << endl;
        m_i = i;
    }
    int m_i;
};
class B{
public:
    int m_j;//基本类型成员变量
    A m_a;//成员子对象
};
int main(void)
{
    B b;
    cout << "基本类型:" << b.m_j << endl;//?
    cout << "类类型:" << b.m_a.m_i << endl;//0
    return 0;
}

#include <iostream>
using namespace std;
class A{
public:
    A(int data = 0){
        cout << "A(int=0)" << endl;
        m_data = data;
    }
    //拷贝构造函数
    /*A(const A& that){
        cout << "A(const A&)" << endl;
        m_data = that.m_data;
    }*/
    int m_data;
};
int main(void)
{
    const A a1(100);
    //A a2(a1);//拷贝构造
    A a2 = a1;//和上面写法等价
    cout << a1.m_data << endl;//100
    cout << a2.m_data << endl;//100
    return 0;
}

#include <iostream>
using namespace std;
class Student{
public:
    //先定义成员变量,再赋初值
    /*
    Student(const string&name,int age,int no){
        cout << "构造函数" << endl;
        m_name = name;
        m_age = age;
        m_no = no;
    }*/
    //定义成员变量同时初始化
    Student(const string&name,int age,int no)
        :m_name(name),m_age(age),m_no(no){}
    void who(void){
        cout << "我叫" << m_name << ",今年" <<
            m_age << "岁,学号是" << m_no <<
                endl;
    }
private:
    string m_name;
    int m_age;
    int m_no;
};
int main(void)
{
    //创建对象/实例化对象/构造对象
    //(...):指定构造函数需要的实参
    Student s("张飞",28,10011);
    s.who();
    //构造函数不能显式调用
    //s.Student("张三",29,10012);
    return 0;
}

#include <iostream>
using namespace std;
class Student{
public:
    Student(const string&name,int age,int no){
        cout << "构造函数" << endl;
        m_name = name;
        m_age = age;
        m_no = no;
    }       
    void who(void){
        cout << "我叫" << m_name << ",今年" <<
            m_age << "岁,学号是" << m_no <<
                endl;
    }
private:
    string m_name;
    int m_age;
    int m_no;
};
int main(void)
{
    //创建对象/实例化对象/构造对象
    //(...):指定构造函数需要的实参
    //Student s("张飞",28,10011);
    Student s = Student("张飞",28,10011);
    s.who();
    //在栈区创建多个对象
    Student sarr[3] = {
        Student("貂蝉",20,10012),
        Student("小乔",22,10013),
        Student("孙尚香",25,10014)};    
    sarr[0].who();
    sarr[1].who();
    sarr[2].who();
    //在堆区创建/销毁单个对象
    Student* ps =
        new Student("扈三娘",30,10015);
    ps->who();//(*ps).who()
    delete ps;
    ps = NULL;
   
    //在堆区创建/销毁多个对象
    Student* parr = new Student[3]{
        Student("孙二娘",35,10016),
        Student("白骨精",40,10017),
        Student("潘金莲",36,10018)};
    parr[0].who();//(*(parr+0)).who()
    parr[1].who();//(*(parr+1)).who()
    parr[2].who();
   
    delete[] parr;
    parr = NULL;
    return 0;
}