C++类的定义 简单的程序 求改错
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有一处错误，弄不出来，求各位帮改，加注释就好~
#include <iostream>
#include <string>
using namespace std;
class instrument
public:instrument()
virtual void Play()
cout << "instrument" << " is playing !" <<endl;
;
void Print(intrument &ins)
ins.show()
class instrPiano:public instrument
public:
void Play()
cout << "Piano" << " is playing !" << endl;
;
class instrSax:public instrument
public:
void Play()
cout << "Sax" << " is playing !" << endl;
;
class instrFlute:public instrument
public:
void Play()
cout << "Flute" << " is playing !" << endl;
;
void Play(instrument m)
m.Play();
int main()
instrument instr;
instrPiano instrPia;
instrSax instrSax;
instrFlute instrFlu;
Play(instr);
Play(instrPia);
Play(instrSax);
Play(instrFlu);
/*
instrument is playing !
Piano is playing !
Sax is playing !
Flute is playing !
Press any key to continue
*/
#include <iostream>#include <string>
using namespace std;
class instrument
public:
instrument()
virtual void Play()
cout << "instrument" << " is playing !" << endl;
;
void Print(instrument &ins)
ins.Play(); // ins.show()
class instrPiano:public instrument
public:
void Play()
cout << "Piano" << " is playing !" << endl;
;
class instrSax:public instrument
public:
void Play()
cout << "Sax" << " is playing !" << endl;
;
class instrFlute:public instrument
public:
void Play()
cout << "Flute" << " is playing !" << endl;
;
void Play(instrument &m)
m.Play();
int main()
instrument instr;
instrPiano instrPia;
instrSax instrSax;
instrFlute instrFlu;
Play(instr);
Play(instrPia);
Play(instrSax);
Play(instrFlu);
return 0;
参考技术A void Print(instrument &ins)
ins.Play();
追问
程序是过了 但结果不对额...我是想输出某个乐器是可以play的 但是输出的都是instrument is playing 求亲再帮看看...
追答void Play(instrument *m)
m->Play();
int main()
instrument instr;
instrPiano instrPia;
instrSax instrSa;
instrFlute instrFlu;
Play(&instr);
Play(&instrPia);
Play(&instrSa);
Play(&instrFlu);
return 0;
理解错了
把show改了之后 程序是过了 但结果不对额...我是想输出某个乐器是可以play的 但是输出的都是instrument is playing 求亲再帮看看.
追答你应该是想用多态性吧？
如果用多态性，先定义一个指向基类的指针，在用这个指针指向不同的派生类，你的那个show函数可以不要的其他的都不用改就把主函数改一下就可以了，我把整个代码给你：
#include
#include
using namespace std;
class instrument
public:
instrument()
virtual void Play()
cout Play();
*/
class instrPiano:public instrument
public:
void Play()
cout Play();
p=&instrPia;
p->Play();
p=&instrSax;
p->Play();
p=&instrFlu;
p->Play();
return 0;
实验2：函数重载函数模板简单类的定义和实现
实验目的
1. 掌握c++中函数的声明、定义、调用和参数传递方式
2. 掌握c++中带有默认形参值的函数声明和定义方法
3. 理解函数重载，掌握c++中函数重载的实现方式
4. 理解函数模板，掌握c++中函数模板的简单使用
5. 理解面向对象的抽象和封装，掌握c++中类的定义、实现和使用方法
实验准备
1. 函数的声明、定义、调用、参数传递方法
2. 带有默认形参值的函数
3. 函数重载
4. 函数模板(9.1.1节 + 9.3节) 其中，9.3节，理解3个常用的排序算法和两个常用的查找算法
5. 类的定义、实现和使用方法
编程内容
函数重载编程练习
编写重载函数add()，实现对int型，double型，Complex型数据的加法。在main()函数中定义不同类型 数据，调用测试。（附程序框架，见本文档附1)
函数模板编程练习
编写实现快速排序函数模板，并在main()函数中，定义不同类型数据，调用测试。（算法可参考这里， 内有排序示意图及算法逻辑）
类的定义、实现和使用编程练习
设计并实现一个用户类User，并在主函数中使用和测试这个类。具体要求如下： 每一个用户有用户名(name), 密码(passwd)，联系邮箱(email)三个属性。 支持设置用户信息setInfo()。允许设置信息时密码默认为6个1，联系邮箱默认为空串。 支持打印用户信息printInfo()。打印用户名、密码、联系邮箱。其中，密码以6个*方式显示。 支持修改密码changePasswd(),。在修改密码前，要求先输入旧密码，验证无误后，才允许修改。 如果输入旧密码时，连续三次输入错误，则提示用户稍后再试，暂时退出修改密码程序。 在main()函数中创建User类实例，测试User类的各项操作（设置用户信息，修改密码，打印用户信 息）
User类功能的完善及拓展丰富(===选做===）
自行设计。在前述内容的基础上，对代码和功能做完善，使其更符合实际应用场景。比如: 支持修改邮箱；用户设置邮箱时对邮箱地址合法性的检测提示（比如是否包含@） 用户更改密码时，当用户输入旧密码和新密码时，屏幕上均以星号代替，而不会显示用户实际 输入的密码；设置密码时对密码的长度、合法性进行有效性校验，等等 。。。
实验结论
1.重载函数add()
Code:
1 //Add()函数重载 2 #include<iostream> 3 #include<cstdlib> 4 using namespace std; 5 struct Complex 6 { 7 double real; 8 double imaginary; 9 }; 10 11 int add(int, int); 12 double add(double, double); 13 Complex add(Complex, Complex); 14 int main() { 15 16 int x, y; 17 cout << "Enter two integers:"; 18 cin >> x >> y; 19 cout << "Their sum is:" << add(x, y) << endl; 20 //双精度型 21 double m, n; 22 cout << "Enter two decimals:"; 23 cin >> m >> n; 24 cout << "Their sum is:" << add(m, n) << endl; 25 //复数 26 Complex k, l;; 27 cout << "Enter two plurals`real part:"; 28 cin >> k.real >> l.real; 29 cout << "Enter two plurals`imaginary part:"; 30 cin >> k.imaginary >> l.imaginary; 31 cout << "Their sum is:" << add(k, l).real << "+" << add(k, l).imaginary << "i" << endl; 32 system("pause"); 33 return 0; 34 } 35 //整型数 36 int add(int a, int b) 37 { 38 int sum; 39 sum = a + b; 40 return sum; 41 } 42 //双精度型数 43 double add(double a, double b) 44 { 45 double sum; 46 sum = a + b; 47 return sum; 48 } 49 //复数 50 Complex add(Complex a, Complex b) 51 { 52 Complex sum; 53 sum.real = a.real + b.real; 54 sum.imaginary = a.imaginary + b.imaginary; 55 return sum; 56 }
Screenshot:
2.快速排序函数模板
main函数：
1 #include<iostream> 2 #include<cstdlib> 3 #include<ctime> 4 #include"quicksort.h" 5 #include"output.h" 6 using namespace std; 7 int main() 8 { 9 //int 10 int list[50],i,a; 11 cout << "Enter the number（integer） you want to sort(1-50):"; 12 cin >> i; 13 cout << "Enter the number:"<<endl; 14 for (a = 0; a <i; a++) 15 { 16 cin >>list[a]; 17 } 18 cout << "The list(integer) before sort is:" << endl; 19 output(list, i); 20 cout << "The list(integer) after sorted is:" << endl; 21 quicksort(list, 0, i - 1); 22 output(list, i ); 23 //double 24 double listd[50],c; 25 cout << "Enter the number（decimal） you want to sort(1-50):"; 26 cin >> i; 27 cout << "Enter the number:" << endl; 28 for (a = 0; a <i; a++) 29 { 30 cin >> listd[a]; 31 } 32 cout << "The list(decimal) before sort is:" << endl; 33 output(listd, i); 34 quicksort(listd, 0, i - 1); 35 cout << "The list(decimal) after sorted is:" << endl; 36 output(listd, i); 37 system("pause"); 38 return 0; 39 }
quicksort函数：
1 #ifndef QUICKSORT_H 2 #define QUICKSORT_H 3 template<class T> 4 void quicksort(T list[], int lo, int hi) 5 { 6 if (lo < hi) 7 { 8 T x = list[lo]; 9 int a, b = 0, c = 0, jud = 0, k = lo; 10 for (a = 1; a <= hi - lo; a++) 11 { 12 if (jud == 0) 13 { 14 if (list[hi - b] < x) 15 { 16 list[k] = list[hi - b]; 17 list[hi - b] = x; 18 k = hi - b; 19 b++; 20 jud = 1; 21 continue; 22 } 23 else 24 { 25 b++; 26 continue; 27 } 28 } 29 else 30 { 31 if (list[lo + c + 1] > x) 32 { 33 list[k] = list[lo + c + 1]; 34 list[lo + c + 1] = x; 35 k = lo + c + 1; 36 c++; 37 jud = 0; 38 continue; 39 } 40 else 41 { 42 c++; 43 continue; 44 } 45 } 46 } 47 quicksort(list, lo, k-1); 48 quicksort(list, k+1, hi); 49 } 50 } 51 #endif
output函数：
1 #ifndef OUTPUT_H 2 #define OUTPUT_H 3 #include<iostream> 4 #include<iomanip> 5 using namespace std; 6 template<class T> 7 void output(T list[], int hi) 8 { 9 int x,i=0; 10 for (x = 0; x < hi; x++) 11 { 12 i++; 13 cout <<setw(5)<< list[x] << " "; 14 if (i % 6 == 0&&x!=hi-1) 15 cout << endl; 16 } 17 cout <<endl; 18 } 19 #endif
Screensort；
3：用户类User
Code（测试）：
1 #include <iostream> 2 #include <string> 3 #include<cstdlib> 4 #include<conio.h> 5 using namespace std; 6 // User类的声明 7 class User 8 { 9 public: 10 void setInfo(string newn, string newp = "111111", string newe = ""); 11 void changePasswd(); 12 void printInfo(); 13 void changeemail(); 14 15 private: 16 string name; 17 string passwd; 18 string email; 19 }; 20 //输入字符串，显示* 21 string enter() 22 { 23 char ch; 24 string outer; 25 while ((ch = _getch())!=‘ ‘) 26 { 27 outer += ch; 28 cout << "*"; 29 } 30 cout << endl; 31 return outer; 32 } 33 //初始化信息 34 void User::setInfo(string newn, string newp/*="111111"*/, string newe/*=""*/) 35 { 36 name = newn; 37 passwd = newp; 38 email = newe; 39 } 40 41 //修改密码 42 void User::changePasswd() 43 { 44 cout << "Enter the old passwd:"; 45 string outer; 46 int jud = 1; 47 outer = enter(); 48 while (outer != passwd) 49 { 50 cout << "Passwd input error,please re-enter again:"; 51 outer = enter(); 52 jud++; 53 if (jud == 3) 54 break; 55 } 56 if (outer != passwd) 57 cout << "Please try after a while. "; 58 else 59 { 60 cout << "Please enter the new passwd:"; 61 passwd = enter(); 62 do 63 { 64 cout << "Please enter the new passwd again:"; 65 outer=enter(); 66 if (outer != passwd) 67 { 68 cout << "Passwd input error,please change the new passwd:"; 69 passwd = enter(); 70 } 71 else 72 break; 73 } while (true); 74 cout << "Finish changepasswd." << endl; 75 } 76 } 77 //修改邮箱 78 void User::changeemail() 79 { 80 string outer,ch; 81 cout << "Enter the new email:"; 82 cin >> outer; 83 int a,b,jud; 84 do 85 { 86 jud = 0; 87 b = outer.length(); 88 for (a = 0; a < b; a++) 89 if (outer.substr(a, 1) == "@") 90 jud++; 91 if (jud == 0) 92 { 93 cout << "Wrong format,please enter again:"; 94 cin >> outer; 95 } 96 else 97 cout << "Finish change email." << endl; 98 } while (jud == 0); 99 email = outer; 100 } 101 //打印至屏幕 102 void User::printInfo() 103 { 104 int y,x = passwd.length(); 105 string outerx; 106 for (y = 1; y <= x; y++) 107 outerx += ‘*‘; 108 cout << "name:" << name << endl; 109 cout << "passwd:" << outerx<< endl; 110 cout << "email:" << email << endl; 111 } 112 int main() 113 { 114 cout << "testing 1......" << endl; 115 // 测试1 116 User user1; 117 user1.setInfo("Leonard"); 118 user1.printInfo(); 119 user1.changePasswd(); 120 user1.printInfo(); 121 cout << endl << "testing 2......" << endl << endl; 122 // 测试2 123 User user2; 124 user2.setInfo("Jonny", "92197", "[email protected]"); 125 user2.printInfo(); 126 system("pause"); 127 return 0; 128 }
Screensort：
功能完善
Code：
1 #include <iostream> 2 #include <string> 3 #include<cstdlib> 4 #include<conio.h> 5 using namespace std; 6 // User类的声明 7 class User 8 { 9 public: 10 void setInfo(string newn, string newp = "111111", string newe = ""); 11 void changePasswd(); 12 void printInfo(); 13 void changeemail(); 14 15 private: 16 string name; 17 string passwd; 18 string email; 19 }; 20 //输入字符串，显示* 21 string enter() 22 { 23 char ch; 24 string outer; 25 while ((ch = _getch())!=‘ ‘) 26 { 27 outer += ch; 28 cout << "*"; 29 } 30 cout << endl; 31 return outer; 32 } 33 //初始化信息 34 void User::setInfo(string newn, string newp/*="111111"*/, string newe/*=""*/) 35 { 36 name = newn; 37 passwd = newp; 38 email = newe; 39 } 40 41 //修改密码 42 void User::changePasswd() 43 { 44 cout << "Enter the old passwd:"; 45 string outer; 46 int jud = 1; 47 outer = enter(); 48 while (outer != passwd) 49 { 50 cout << "Passwd input error,please re-enter again:"; 51 outer = enter(); 52 jud++; 53 if (jud == 3) 54 break; 55 } 56 if (outer != passwd) 57 cout << "Please try after a while. "; 58 else 59 { 60 cout << "Please enter the new passwd:"; 61 passwd = enter(); 62 do 63 { 64 cout << "Please enter the new passwd again:"; 65 outer=enter(); 66 if (outer != passwd) 67 { 68 cout << "Passwd input error,please change the new passwd:"; 69 passwd = enter(); 70 } 71 else 72 break; 73 } while (true); 74 cout << "Finish changepasswd." << endl; 75 } 76 } 77 //修改邮箱 78 void User::changeemail() 79 { 80 string outer,ch; 81 cout << "Enter the new email:"; 82 cin >> outer; 83 int a,b,jud; 84 do 85 { 86 jud = 0; 87 b = outer.length(); 88 for (a = 0; a < b; a++) 89 if (outer.substr(a, 1) == "@") 90 jud++; 91 if (jud == 0) 92 { 93 cout << "Wrong format,please enter again:"; 94 cin >> outer; 95 } 96 else 97 cout << "Finish change email." << endl; 98 } while (jud == 0); 99 email = outer; 100 } 101 //打印至屏幕 102 void User::printInfo() 103 { 104 int y,x = passwd.length(); 105 string outerx; 106 for (y = 1; y <= x; y++) 107 outerx += ‘*‘; 108 cout << "name:" << name << endl; 109 cout << "passwd:" << outerx<< endl; 110 cout << "email:" << email << endl; 111 } 112 int main() 113 { 114 User you; 115 //输入用户名 116 string name; 117 cout << "Enter your name(password:111111):"; 118 cin >> name; 119 you.setInfo(name); 120 //操作列表 121 cout << "Choose your operation" << endl; 122 cout << "1--change password"<<endl; 123 cout << "2-change email"<<endl; 124 cout << "3-print on the screen" << endl; 125 cout << "0-EXIT" << endl; 126 int x=1; 127 while (x!=0) 128 { 129 cout << "Your operation is:"; 130 cin >> x; 131 switch (x) 132 { 133 case 1: 134 you.changePasswd(); 135 continue; 136 case 2: 137 you.changeemail(); 138 continue; 139 case 3: 140 you.printInfo(); 141 continue; 142 default: 143 cout<<"Wrong operation,please enter again."<<endl; 144 } 145 } 146 system("pause"); 147 return 0; 148 }
Screensort：
实验总结与体会
1.写预处理命令时记得大写
2.写快速排序时注意数组从零开始
3.实验一中单独建立一个复数类会更方便计算
4.在一定限度内，快速排序速度最快，但当数据过大时，就会占用过多内存，这时用其他的排序法会更好
5.实验三中单独建立一个声明User类的头文件会使代码可读性更高，更加方便查找bug并修改
6.函数重载减少了函数名的数量，使程序更加面向对象化
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