一、实验目的：
1、掌握通过继承机制派生出新类的方法
2、掌握基类成员在不同派生方式下访问权限的变化
3、了解虚基类的用法
二、实验内容
1、给出一段有错误的程序，分析访问属性。上机调试，使之能正确运行并得到正确结果。
2、分别定义Person类、Employee类、Student类以及在职研究生类PartTime_Graduate_Student，并且画出相应的继承层次图。
三、UML类图
1 #ifndef _PERSON_H 2 #define _PERSON_H 3 4 #include<string> 5 using namespace std; 6 7 class Person 8 { 9 private: 10 string name; 11 char sex; 12 int age; 13 public: 14 Person(); 15 Person(string iname,char isex,int iage); 16 void showName(); 17 void showSex(); 18 void showAge(); 19 }; 20 #endif 21 22 //person.cpp 23 #include "person.h" 24 #include <iostream> 25 #include<string> 26 27 using namespace std; 28 Person::Person() 29 { 30 cout<<"name:"; 31 cin>>name; 32 cout<<"sex:"; 33 cin>>sex; 34 cout<<"age:"; 35 cin>>age; 36 cout<<"construct a Person."<<endl; 37 } 38 Person::Person(string iname,char isex,int iage):name(iname),sex(isex),age(iage) 39 { 40 cout<<"iconstruct a Person."<<endl; 41 } 42 void Person::showName(){cout<<"name: "<<name<<endl;} 43 void Person::showSex(){cout<<"sex: "<<sex<<endl;} 44 void Person::showAge(){cout<<"age: "<<age<<endl;} 45 46 47 //employee.h 48 #include "person.h" 49 50 class Employee:virtual public Person 51 { 52 private: 53 string pos;//职务 54 double empnum;//员工号 55 public: 56 Employee(); 57 Employee(string iname,char isex,int iage,string ipos,double iempnum); 58 void showPos(); 59 void showEmpnum(); 60 void showEmp(); 61 }; 62 63 //employee.cpp 64 #include "employee.h" 65 #include <iostream> 66 #include<string> 67 68 using namespace std; 69 70 Employee::Employee() 71 { 72 cout<<"position:"; 73 cin>>pos; 74 cout<<"empnum:"; 75 cin>>empnum; 76 cout<<"construct an Employee."<<endl; 77 } 78 Employee::Employee(string iname,char isex,int iage,string ipos,double iempnum):Person(iname,isex,iage),pos(ipos),empnum(iempnum) 79 { 80 cout<<"iconstruct an Employee."<<endl; 81 } 82 void Employee::showPos(){cout<<"position: "<<pos<<endl;} 83 void Employee::showEmpnum(){cout<<"employee number: "<<empnum<<endl;} 84 void Employee::showEmp() 85 { 86 showName(); 87 showSex(); 88 showAge(); 89 showPos(); 90 showEmpnum(); 91 } 92 93 //student.h 94 #include "person.h" 95 96 class Student:virtual public Person 97 { 98 private: 99 string maj;//专业 100 double stunum;//学号 101 public: 102 Student(); 103 Student(string iname,char isex,int iage,string imaj,double istunum); 104 void showStunum(); 105 void showMaj(); 106 void showStu(); 107 }; 108 109 //student.cpp 110 #include "student.h" 111 #include <iostream> 112 #include<string> 113 114 using namespace std; 115 116 Student::Student() 117 { 118 cout<<"major:"; 119 cin>>maj; 120 cout<<"Student_number:"; 121 cin>>stunum; 122 cout<<"construct a Student."<<endl; 123 } 124 Student::Student(string iname,char isex,int iage,string imaj,double istunum):Person(iname,isex,iage),maj(imaj),stunum(istunum) 125 { 126 cout<<"iconstruct a Student."<<endl; 127 } 128 void Student::showStunum(){cout<<"student number: "<<stunum<<endl;} 129 void Student::showMaj(){cout<<"major: "<<maj<<endl;} 130 void Student::showStu() 131 { 132 showName(); 133 showSex(); 134 showAge(); 135 showMaj(); 136 showStunum(); 137 } 138 139 //PartTime_Graduate_Student.h 140 #include "employee.h" 141 #include "student.h" 142 143 class PartTime_Graduate_Student:public Employee,public Student 144 { 145 private: 146 string graduate_school;//graduate_school 147 public: 148 PartTime_Graduate_Student(); 149 PartTime_Graduate_Student(const string &iname,char isex,int iage,const string &ipos,double iempnum,const string &imaj,double istunum,const string &igs); 150 void showSchool(); 151 void showAll(); 152 }; 153 154 //PartTime_Graduate_Student.cpp 155 #include "PartTime_Graduate_Student.h" 156 #include <iostream> 157 #include<string> 158 159 using namespace std; 160 161 PartTime_Graduate_Student::PartTime_Graduate_Student() 162 { 163 cout<<"graduate school:"; 164 cin>>graduate_school; 165 cout<<"construct a PartTime_Graduate_Student."<<endl; 166 } 167 PartTime_Graduate_Student::PartTime_Graduate_Student(const string &iname,char isex,int iage,const string &ipos,double iempnum,const string &imaj,double istunum,const string &igs):Person(iname,isex,iage),Employee(iname,isex,iage,ipos,iempnum),Student(iname,isex,iage,imaj,istunum),graduate_school(igs) 168 { 169 cout<<"iconstruct a PartTime_Graduate_Student."<<endl; 170 } 171 void PartTime_Graduate_Student::showSchool(){cout<<"graduate school: "<<graduate_school<<endl;} 172 void PartTime_Graduate_Student::showAll() 173 { 174 showName(); 175 showSex(); 176 showAge(); 177 showPos(); 178 showEmpnum(); 179 showMaj(); 180 showStunum(); 181 showSchool(); 182 } 183 184 //main.cpp 185 #include "PartTime_Graduate_Student.h" 186 #include <iostream> 187 #include<string> 188 189 using namespace std; 190 191 int main() 192 { 193 PartTime_Graduate_Student pa("zzy",‘f‘,18,"manager",2001,"computer science",2101,"ouc"); 194 pa.showAll(); 195 PartTime_Graduate_Student pb; 196 pb.showAll(); 197 return 0; 198 }
1.virtual继承: 为了解决多重继承中有共同的基类(菱形继承)时的问题. 需要使用virtual继承的方式.
2.出现报错“error: expected primary-expression before XXX”(pgs类中的有参构造函数)因为XXX变量的调用时，前方多加了变量类型关键字，删掉即可。
3.warning "will be initialized after [-Wreorder]（student类中stunum：double和major：string出现和初始化的顺序不对应）原因：构造函数时，初始化成员变量的顺序要与类声明中的变量顺序相对应，若不对应，则出现如此警告。解决方法就是按照顺序进行初始化，或者调整类中数据成员（变量）出现的顺序。在student类中stunum：double先出现，major：string后出现，但在初始化时却先major后stunum，故出错。调整major和stunum在类中定义的顺序后解决。
4.no matching function for call to `xushu::set(xushu)‘（主函数中用psg创建有参对象pa时，没有写igs对应的实参）编译器没有找到签名为 xushu::set(xushu)的函数。要么是函数写错了，要么是调用的时候写错了。
1 #include<iostream> 2 using namespace std;//修改 3 4 class X{ 5 public: 6 X(int x){a=x;} 7 void showX(){cout<<"a="<<a<<endl;} 8 private: 9 int a; 10 }; 11 12 class Y: private X{ 13 public: 14 Y(int x,int y):X(x){b=y;}//修改 15 void showY( ) 16 { 17 showX();//修改 18 cout<<"b="<<b<<endl; 19 } 20 void showX()//修改 21 { 22 return X::showX(); 23 } 24 private: 25 int b; 26 }; 27 28 class Z: public Y{ 29 public: 30 Z(int x, int y, int z):Y(x,y){ c=z; } 31 void showZ() 32 { 33 showY();//修改 34 cout<<"c="<<c<<endl; 35 } 36 private: 37 int c; 38 }; 39 40 int main( ) 41 { 42 Z obj(10, 20, 30); 43 obj.showX( ); 44 obj.showY( ); 45 obj.showZ( ); 46 } 47 /* 48 49 Requirement: 50 51 *Y is a private subclass of X. 52 53 *Z is a public subclass of Y. 54 55 *a, b, and c are encapsulated data members. 56 57 *Do not change the interface in function main( ). 58 59 *Output: 60 61 a=10 62 63 a=10 64 65 b=20 66 67 a=10 68 69 b=20 70 71 c=30 72 */
原文：https://www.cnblogs.com/satellite2021/p/14897949.html