C++ 实验2：函数重载、函数模板、简单类的定义和实现

1.函数重载编程

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。

#include <iostream>
using namespace std;
struct complex {
    double real;
    double imaginary;
};
int add(int x2, int y2)
{
    return x2 + y2;
}
double add(double a1, double b1)
{
    return a1 + b1;
}
complex add(complex a, complex b)
{
    complex c;
    c.imaginary = a.imaginary + b.imaginary;
    c.real = a.real + b.real;
    return c;
}

int add(int x2, int y2);
double add(double a1, double b1);
complex add(complex a, complex b);
int main()
{
    int x = , y = , s1;
    double m = 4.2, n =1.5, s2;
    complex complex1, complex2, complex3;
    complex1.real = , complex1.imaginary = ;
    complex2.real = , complex2.imaginary = ;
    s1 = add(x, y);
    s2 = add(m, n);
    complex3 = add(complex1, complex2);
    cout << s1 << endl;
    cout << s2 << endl;
    cout << complex3.real << "+" << complex3.imaginary << "i" << endl;
    system("pause");
    return ;
}

2.函数模板编程

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。

#ifndef Quicksort
#define Quicksort
template <class T>
void quicksort(T s[], int low, int high) {
    int a, b, c = ;
    T f, ex;
    a = low; b = high - ; f = s[(low + high) / ];
    if (a < b) {
        while (a < b) {
            while (a < b&&f < s[b])
                b--;
            while (a < b&&f > s[a])
                a++;
            if (a >= b) c = b;
            else { ex = s[a]; s[a] = s[b]; s[b] = ex; }
        }
        quicksort(s, low, c);
        quicksort(s, c + , high);
    }
}
#endif

#include <iostream>
#include <iomanip>
#include "quicksort.h"
using namespace std;
int main()
{
    int i;
    int a[] = { ,,,, };
    double b[] = { 5.5,8.5,9.9,2.5,3.6 };
    quicksort(a, , );
    quicksort(b, , );
    for (i=;i<;i++)
        cout << setw() << a[i];
    cout << endl;
    for (i=;i<;i++)
        cout << setw() << b[i];
    cout << endl;
    system("pause");
    return ;
}

3.类的定义、实现和使用编程

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。

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）

#include<iostream>
#include<string>
using namespace std;
class User {
public:
    User(string yourname, string yourpasswd, string youremail);
    User() {
        name = "";
        password = "";
        email = "";
    }
    void setInfo(string yourname = "", string yourpasswd = "", string youremail = "");
    void changePasswd();
    void printInfo();
private:
    string name;
    string password;
    string email;
};
void User::setInfo(string yourname, string yourpasswd, string youremail) {
    if (name == " ") cin >> yourname;
    name = yourname;
    if (password == " ") cin >> yourpasswd;
    password = yourpasswd;
    if (email == " ") cin >> youremail;
    email = youremail;
}
void User::changePasswd() {
    string yourpassword;
    int i = ;
    cout << "please input password:";cin >> yourpassword;
    while (password != yourpassword && i < )
    {
        cout << "wrong,please input it again:";cin >> yourpassword;
        i++;
    }
    if (password != yourpassword && i == )
        cout << "please try later" << endl;
    if (password == yourpassword)
    {
        cout << "please input your  password:";cin >> yourpassword;
    }
}
void User::printInfo() {
    cout << "Name: " << name << endl;
    cout << "Password: " << "******" << endl;
    cout << "Email: " << email << endl;
}

#include<iostream>
#include<iomanip>
#include"user.h"
int main() {
    cout << "testing 1......" << endl;
    User user1;
    user1.setInfo("Leonard");
    user1.printInfo();
    user1.changePasswd();
    user1.printInfo();
    cout << endl << "testing 2......" << endl << endl;
    User user2;
    user2.setInfo("Jonny", "", "xyz@hotmail.com");
    user2.printInfo();
    system("pause");
    return ;
}

实验总结：

1.对于快速排序不是很理解，所以不知道怎么写，去问了同学和看了她的程序还是不太理解，所以最后基本上参考了同学的程序；

2.函数重载和类的定义基本上用了老师给的程序框架，但在编程的过程中还是很费劲；

3.以上问题说明我还没有掌握这些知识点，还有以上程序出现的不足之处，还请各位多多指教。

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