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C++第六天
今天讲了纯虚函数,虚析构函数,友元和运算符重载,讲的东西感觉有点多,但是题目做的也多,即使还是写不出来也是有印象了。今天老师给我们留的作业内容是课上都讲过的,也算是有例题,原本以为把例题改一下就可以了,没想到没用,错误百出,试着改错也改不出来,明天看看老师是咋改的吧。
//homoework:
#include
#include
using namespace std;
class Teacher
{
public:
Teacher(){}
Teacher(string name, float base, float subsidy, int num)
{
m_strName = name;
m_fBaseSalary = base;
m_fSubsidy = subsidy;
m_iNum = num;
}
int getNum()
{
return m_iNum;
}
virtual float salary()=0;
void show()
{
cout << "名字:" << m_strName << " 基本工资:" << m_fBaseSalary << " 补贴:" << m_fSubsidy << " 课时:" << m_iNum << " 总工资:" << salary() << endl;
}
private:
string m_strName;
float m_fBaseSalary;
float m_fSubsidy;
int m_iNum;
};
class Lecturer: public Teacher
{
public:
Lecturer(){}
Lecturer(string name, float base, float subsidy, int num)
: Teacher(name, base, subsidy, num)
{}
float salary()
{
return 2000+20*getNum();
}
};
class Professor: public Teacher
{
public:
Professor(string name, float base, float subsidy, int num)
: Teacher(name, base, subsidy, num)
{}
float salary()
{
return 5000+50*getNum();
}
};
class AssociateProfessor: public Teacher
{
public:
AssociateProfessor(string name, float base, float subsidy, int num)
: Teacher(name, base, subsidy, num)
{}
float salary()
{
return 3000+30*getNum();
}
};
int main(void)
{
Lecturer lec("lisi", 2000, 20, 90);
lec.show();
AssociateProfessor ap("wangwu", 3000,30,70);
ap.show();
Professor pro("zhaoliu", 5000, 50, 100);
pro.show();
return 0;
}
//虚析构函数
#include
#include
using namespace std;
class A
{
public:
A(const char *data=NULL)
{
m_data = NULL;
if (NULL != data)
{
int len = strlen(data);
m_data = new char[len+1];
strcpy(m_data, data);
}
cout << "A(...)" << endl;
}
//若存在继承派生的情况,则一般将基类的析构函数定义为虚函数,可以通过基类的指针来完全释放派生类的对象
virtual ~A()
{
if (NULL != m_data)
{
delete []m_data;
m_data = NULL;
}
cout << "~A()" << endl;
}
private:
char *m_data;
};
class B: public A
{
public:
B(const char *data=NULL, const char *a=NULL)
: A(a)
{
m_data = NULL;
if (NULL != data)
{
int len = strlen(data);
m_data = new char[len+1];
strcpy(m_data, data);
}
cout << "B(...)" << endl;
}
//若基类的析构函数为虚函数,则派生类中的析构函数默认为虚函数
~B()
{
if (NULL != m_data)
{
delete []m_data;
m_data = NULL;
}
cout << "~B()" << endl;
}
private:
char *m_data;
};
int main(void)
{
#if 0
A *pa = new A("hello");
delete pa;
B *pb = new B("asa", "ewqqqq");
delete pb;
#endif
A *pp = new B("wqq", "qwwqqqq");
delete pp;
return 0;
}
//重载加减运算符
#include
using namespace std;
class Complex
{
public:
Complex(float real=0, float vir=0)
{
m_fReal = real;
m_fVir = vir;
}
void show()
{
cout << m_fReal << '+' << m_fVir << 'i' << endl;
}
friend Complex operator+(Complex &c1, Complex &c2);
private:
float m_fReal;
float m_fVir;
};
Complex operator+(Complex &c1, Complex &c2)
{
Complex c;
c.m_fReal = c1.m_fReal+c2.m_fReal;
c.m_fVir = c1.m_fVir+c2.m_fVir;
return c;
}
int main(void)
{
Complex c1(3, 7);
Complex c2(13, 5);
Complex c3 = c1 + c2;
c3.show();
return 0;
}
//从载输出输入运算符
#include
using namespace std;
class Complex
{
public:
Complex(float real=0, float vir=0)
{
m_fReal = real;
m_fVir = vir;
}
friend Complex operator+(Complex &c1, Complex &c2);
friend Complex operator-(Complex &c1, Complex &c2);
friend ostream& operator<<(ostream& out, const Complex &com);
private:
float m_fReal;
float m_fVir;
};
Complex operator+(Complex &c1, Complex &c2)
{
Complex c;
c.m_fReal = c1.m_fReal+c2.m_fReal;
c.m_fVir = c1.m_fVir+c2.m_fVir;
return c;
}
Complex operator-(Complex &c1, Complex &c2)
{
Complex c;
c.m_fReal = c1.m_fReal-c2.m_fReal;
c.m_fVir = c1.m_fVir-c2.m_fVir;
return c;
}
//cout << 90;
ostream& operator<<(ostream& out, const Complex &com)
{
out << '('< //重载自增
#include
#include
using namespace std;
class Time
{
public:
Time(int min, int sec)
{
m_iMinute = min;
m_iSecond = sec;
}
Time &operator++()//前加加
{
m_iSecond++;
if (60 == m_iSecond)
{
m_iSecond= 0;
m_iMinute++;
if (60 == m_iMinute)
{
m_iMinute = 0;
}
}
return *this;
}
friend ostream &operator<<(ostream& out, const Time &time);
private:
int m_iMinute;
int m_iSecond;
};
ostream &operator<<(ostream& out, const Time &time)
{
out << time.m_iMinute << ':' << time.m_iSecond;
return out;
}
int main(void)
{
Time t(59, 50);
cout << t << endl;
Time t2 = ++t;
cout << "t:" << t << " t2:" << t2 << endl;
while (1)
{
++t;
cout << t << endl;
sleep(1);
}
return 0;
}
//重载自增
#include
#include
using namespace std;
class Time
{
public:
Time(int min, int sec)
{
m_iMinute = min;
m_iSecond = sec;
}
//后加加
Time operator++(int)
{
Time t = *this;
m_iSecond++;
if (60 == m_iSecond)
{
m_iSecond= 0;
m_iMinute++;
if (60 == m_iMinute)
{
m_iMinute = 0;
}
}
return t;
}
friend ostream &operator<<(ostream& out, const Time &time);
private:
int m_iMinute;
int m_iSecond;
};
ostream &operator<<(ostream& out, const Time &time)
{
out << time.m_iMinute << ':' << time.m_iSecond;
return out;
}
int main(void)
{
Time t(59, 50);
Time t2 = t++;
cout << "t2:" << t2 << " t:" << t < //重载自减
#include
#include
using namespace std;
class Time
{
public:
Time(int min, int sec)
{
m_iMinute = min;
m_iSecond = sec;
}
//后减减
Time &operator--()
{
m_iSecond--;
if (-1 == m_iSecond)
{
m_iSecond= 59;
m_iMinute--;
if (-1 == m_iMinute)
{
m_iMinute = 59;
}
}
return *this;
}
Time operator--(int)
{
Time t = *this;
m_iSecond--;
if (-1 == m_iSecond)
{
m_iSecond= 59;
m_iMinute--;
if (-1 == m_iMinute)
{
m_iMinute = 59;
}
}
return t;
}
friend ostream &operator<<(ostream& out, const Time &time);
private:
int m_iMinute;
int m_iSecond;
};
ostream &operator<<(ostream& out, const Time &time)
{
out << time.m_iMinute << ':' << time.m_iSecond;
return out;
}
int main(void)
{
Time t(59, 50);
Time t2 = t--;
cout << "t2:" << t2 << " t:" << t < //重载赋值运算符
#include
#include
using namespace std;
class MyString
{
public:
~MyString()
{
if (NULL != m_data)
{
delete []m_data;
}
cout << "~MyString()\n";
}
MyString &operator=(const MyString &other)
{
if (this == &other)
{
return *this;
}
if (NULL != m_data)
{
delete []m_data;
m_data = NULL;
}
if (NULL == other.m_data)
{
return *this;
}
m_iLen = other.m_iLen;
m_data = new char[m_iLen+1];
strcpy(m_data, other.m_data);
cout << "operator=(...)\n";
}
//拷贝构造函数
MyString(const MyString &other)
{
m_iLen = other.m_iLen;
if (NULL == other.m_data)
{
m_data = NULL;
}
else
{
m_data = new char[m_iLen+1];
if (NULL != m_data)
{
strcpy(m_data, other.m_data);
}
}
cout << "MyString(MyString&)\n";
}
MyString(const char *data = NULL)
{
if (NULL == data)
{
m_data = NULL;
m_iLen = 0;
}
else
{
int len = strlen(data);
m_data = new char[len+1];
if (NULL == m_data)
{
cout << "new failed\n";
return;
}
strcpy(m_data, data);
m_iLen = len;
cout << m_data << ':';
}
cout << "MyString(...)\n";
}
const char *data()
{
return m_data;
}
private:
int m_iLen;
char *m_data;
};
int main(void)
{
MyString s("HelloWorld");
//MyString s2 = s; //MyString s2(s);
//MyString s3;
MyString s3("$$$$$$$$");
s3 = s;
//s3.operator=(s);
return 0;
}
//重载运算符
#include
using namespace std;
class Complex
{
public:
//explicit:防止隐式类型转换
explicit Complex(float real = 0,float vir = 0)
{
m_fReal = real;
m_fVir = vir;
cout << "Complex(...)\n";
}
void show()
{
cout << m_fReal << '+' << m_fVir << 'i' << endl;
}
friend Complex operator+(Complex &c1,Complex &c2);
friend Complex operator-(Complex &c1,Complex &c2);
private:
float m_fReal;
float m_fVir;
};
Complex operator+(Complex &c1,Complex &c2)
{
Complex c;
c.m_fReal = c1.m_fReal+c2.m_fReal;
c.m_fVir = c1.m_fVir+c2.m_fVir;
return c;
}
Complex operator-(Complex &c4,Complex &c5)
{
Complex c;
c.m_fReal = c4.m_fReal-c5.m_fReal;
c.m_fVir = c4.m_fVir-c5.m_fVir;
return c;
}
void fun(Complex com)
{
com.show();
}
int main(int argc,char *argv[])
{
//隐式类型转换
fun(23);
return 0;
}
//重载运算符
#include
using namespace std;
class Complex
{
public:
//explicit:防止隐式类型转换
//explicit Complex(float real=0, float vir=0)
Complex(float real=0, float vir=0)
{
m_fReal = real;
m_fVir = vir;
cout << "Complex(...)\n";
}
void show()
{
cout << '('< 友元:
#include
#include
using namespace std;
class Girl
{
public:
Girl(string name, string phone)
{
m_strName = name;
m_strPhone = phone;
}
//将一个函数定义为类的友元,则可以在该函数中通过对象直接访问类的私有成员
//友元破坏了类的封装性,能不用尽量不用
friend void fun();
private:
string m_strName;
string m_strPhone;
};
void fun()
{
Girl g("阿菲", "1818181818");
cout << g.m_strName << endl;
}
int main(void)
{
fun();
return 0;
}
//重载小括号
#include
using namespace std;
class Test
{
public:
void operator()(int a,int b)
{
int max = a;
if(a < b)
{
max = b;
}
cout << "max:" << max << endl;
}
};
int main(void)
{
Test t;
// t.operator()(34,89);
t(34,89);//函数对象
return 0;
}
//纯虚函数
#include
using namespace std;
class Shape
{
public:
Shape(){}
//纯虚函数
//包含纯虚函数的类称之为抽象类
//抽象类不能定义对象
//抽象类：为了实现多态，统一接口
//派生类中，如果没有对纯虚函数进行定义,则派生类仍然为抽象类，不能定义对象
//若派生类中对纯虚函数进行定义了,则可以生成对象
virtual float area() = 0;
};
class Test: public Shape
{
public:
Test(int i = 90): m_i(i){}
int m_i;
};
class Square: public Shape
{
public:
Square(float w=0): m_fWidth(w)
{}
float area()
{
cout << "Square::area()\n";
return m_fWidth*m_fWidth;
}
private:
float m_fWidth;
};
class Triangle: public Shape
{
public:
Triangle(float b=0, float h=0)
{
m_fBottom = b;
m_fHight = h;
}
float area()
{
cout << "Triangle::area()\n";
return m_fBottom*m_fHight/2;
}
private:
float m_fBottom;
float m_fHight;
};
void show(Shape *pshape)
{
cout << pshape->area() << endl;
}
int main(void)
{
// Shape shape; // X
//Test t(123);
cout << "shape:" << sizeof(Shape) << endl;
return 0;
}
homework:
![图片.png](http://upload-images.jianshu.io/upload_images/4254001-5c7d4033960ac8de.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240