C++学习路线（二十五）

常见错误总结

错误1：对象const问题

#include <iostream>class Man {
public:void walk() {std::cout << "I am walking." << std::endl;}
};int main() {const Man man;man.walk();return 0;
}

原因是Man man是const对象但是调用了非const的成员函数

解决办法1：去掉man前面的const

解决办法2：walk后面加上const

错误2：vector加入的成员是拷贝新成员

#include <iostream>
#include <vector>
using namespace std;class Man {
public:Man(){}void play() {count += 10;cout << "Man is playing" << endl;}int getCount() const {return count;}
private:int count = 0;
};int main() {vector<Man> mans;Man man;man.play();mans.push_back(man);man.play();cout << "Total count: " << man.getCount() << endl;cout << "vector Total count: " << mans[0].getCount() << endl;return 0;
}

错误3：const引用问题

原因:非const引用,不能对const变量进行引用

注意:const引用，可以对非const变量进行引用

错误4：static错误

static方法不能访问实例方法和实例数据成员

Linux学习

1..需要研究 Linux的那些方面?

1)基本命令操作(<50 条命令)

2)Linux 系统编程-服务器开发

2.应该选择 Linux 的哪些发行版本?

Ubuntu

Centos (Redhat 的社区版)
3.使用虚拟机方式还是硬盘安装?

VMware workstation (vmware)

项目练习一

创建一个类，用来表示“玩具”
文具，有以下数据:
名称，价格，产地。
在使用中，需要获取它的名称，价格，产地。

注意:根据自己当前的优惠情况，有一个对外的价格

Toy.h

#pragma once
#include <string>class Toy {
public:Toy();Toy(std::string name, double price, std::string manufacturerLocation);~Toy();std::string getName() const;double getPrice() const;std::string getManufacturerLocation() const;void setDisCount(double discount);
private:std::string name;double price;std::string manufacturerLocation;double discount = 1.0;
};

Toy.cpp

#include "toy.h"Toy::Toy() {}Toy::~Toy() {}
Toy::Toy(std::string name, double price, std::string maufacturerLocation) {this->name = name;this->price = price;this->manufacturerLocation = maufacturerLocation;
}std::string Toy::getName() const {return this->name;
}double Toy::getPrice() const {return this->price * this->discount;
}std::string Toy::getManufacturerLocation() const {return this->manufacturerLocation;
}void Toy::setDisCount(double disCount) {this->discount = disCount;
}

main.cpp

#include <iostream>
#include "toy.h"
using namespace std;int main() {Toy t("car", 1002.123, "中国");cout << t.getName() << t.getPrice() << t.getManufacturerLocation() << endl;t.setDisCount(0.5);cout << t.getPrice();return 0;
}

项目练习二

定义一个或多个类，来描述以下需求:
定义一个类，来表示某模拟养成游戏中人物:

每个人物，有昵称，年龄，性别，配偶，朋友

支持的活动有:结婚，离婚,交友，断交，询问昵称，询问性别，询问年龄,简介等

Human.h

#pragma once
#include <string>
#include <iostream>
#include <vector>
enum Gender {Male,Female
};class Human {
public:int getAge() const;std::string Description() const;Gender getGender() const;std::string getName() const;Human* getMarried() const;std::vector<Human*> getFriend() const;void marry(Human& partner);void divorce();void addFriend(Human& friend_);void removeFriend(Human& friend_);Human();Human(std::string, int, Gender);~Human();private:std::string name;int age;Gender gender;Human* lover = nullptr;std::vector<Human*> friends;
};

Human.cpp

#include "Human.h"
#include <sstream>
Human::Human(){}Human::Human(std::string name , int age , Gender gender) : age(age), name(name), gender(gender) {}
Human::~Human(){}int Human::getAge() const{return age;
}std::string Human::Description() const {std::stringstream ss;ss << "Age: " << age;ss << " Name: " << name;ss << " Gender: " << (gender == Male)? "男" : "女";return ss.str();
}Gender Human::getGender() const{return gender;
}std::string Human::getName() const{return name;
}Human* Human::getMarried() const {return lover;
}std::vector<Human*> Human::getFriend() const {return friends;
}void Human::marry(Human& partner) {if (gender == partner.gender) return;this->lover = &partner;partner.lover = this;
}void Human::divorce() {if (this->lover!= nullptr) {this->lover->lover = nullptr;this->lover = nullptr;}
}void Human::addFriend(Human& friend_) {friends.push_back(&friend_);
}void Human::removeFriend(Human& friend_) {for (auto it = friends.begin(); it != friends.end(); ++it) {if (*it == &friend_) {friends.erase(it);}else {it++;}}
}

main.cpp

#include <iostream>
#include "Human.h"
using namespace std;int main() {Human man1("John", 25, Male);Human women1("Mary", 30, Female);Human man2("Tom", 20, Male);Human women2("Lily", 25, Female);man1.marry(women1);Human* who = man1.getMarried();if (who == NULL) {cout << "Man1 is not married" << endl;}else {cout << "Man1 is married to " << who->getName() << endl;}man1.divorce();who = man1.getMarried();if (who == NULL) {cout << "Man1 is not married" << endl;}else {cout << "Man1 is married to " << who->getName() << endl;}man1.addFriend(man2);man1.addFriend(women2);/*cout << "Woman1 is married to " << who->getMarried()->Description() << endl;*/return 0;
}