实验2：函数重载、函数模板、简单类的定义和实现

实验目的 

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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

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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

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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

 

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1.重载函数add()

Code:

 

//Add()函数重载
#include<iostream> 
#include<cstdlib>
using namespace std;
struct Complex
{
    double real;
    double imaginary;
};

int add(int, int);
double add(double, double);
Complex add(Complex, Complex);
int main() {

    int x, y;
    cout << "Enter two integers:";
    cin >> x >> y;
    cout << "Their sum is:" << add(x, y) << endl;
    //双精度型
    double m, n;
    cout << "Enter two decimals:";
    cin >> m >> n;
    cout << "Their sum is:" << add(m, n) << endl;
    //复数
    Complex k, l;;
    cout << "Enter two plurals`real part:";
    cin >> k.real >> l.real;
    cout << "Enter two plurals`imaginary part:";
    cin >> k.imaginary >> l.imaginary;
    cout << "Their sum is:" << add(k, l).real << "+" << add(k, l).imaginary << "i" << endl;
    system("pause");
    return 0;
}
//整型数
int add(int a, int b)
{
    int sum;
    sum = a + b;
    return sum;
}
//双精度型数
double add(double a, double b)
{
    double sum;
    sum = a + b;
    return sum;
}
//复数
Complex add(Complex a, Complex b)
{
    Complex sum;
    sum.real = a.real + b.real;
    sum.imaginary = a.imaginary + b.imaginary;
    return sum;
}

 

Screenshot:

 

2.快速排序函数模板

main函数：

 

#include<iostream>
#include<cstdlib>
#include<ctime>
#include"quicksort.h"
#include"output.h"
using namespace std;
int main()
{
    //int
    int list[50],i,a;
    cout << "Enter the number（integer） you want to sort(1-50):";
    cin >> i;
    cout << "Enter the number:"<<endl;
    for (a = 0; a <i; a++)
    {
        cin >>list[a];
    }
    cout << "The list(integer) before sort is:" << endl;
    output(list, i);
    cout << "The list(integer) after sorted is:" << endl;
    quicksort(list, 0, i - 1);
    output(list, i );
    //double
    double listd[50],c;
    cout << "Enter the number（decimal） you want to sort(1-50):";
    cin >> i;
    cout << "Enter the number:" << endl;
    for (a = 0; a <i; a++)
    {
        cin >> listd[a];
    }
    cout << "The list(decimal) before sort is:" << endl;
    output(listd, i);
    quicksort(listd, 0, i - 1);
    cout << "The list(decimal) after sorted is:" << endl;
    output(listd, i);
    system("pause");
    return 0;
}

 

quicksort函数：（PS：完全自己想的，比起网上的十分不精简。以后也要优化下结构）

 

#ifndef QUICKSORT_H
#define QUICKSORT_H
template<class T>
void quicksort(T list[], int lo, int hi)
{
    if (lo < hi)
    {
        T x = list[lo];
        int a, b = 0, c = 0, jud = 0, k = lo;
        for (a = 1; a <= hi - lo; a++)
        {
            if (jud == 0)
            {
                if (list[hi - b] < x)
                {
                    list[k] = list[hi - b];
                    list[hi - b] = x;
                    k = hi - b;
                    b++;
                    jud = 1;
                    continue;
                }
                else
                {
                    b++;
                    continue;
                }
            }
            else
            {
                if (list[lo + c + 1] > x)
                {
                    list[k] = list[lo + c + 1];
                    list[lo + c + 1] = x;
                    k = lo + c + 1;
                    c++;
                    jud = 0;
                    continue;
                }
                else
                {
                    c++;
                    continue;
                }
            }
        }
        quicksort(list, lo, k-1);
        quicksort(list, k+1, hi);
    }
}
#endif

 

output函数：

 

#ifndef OUTPUT_H
#define OUTPUT_H
#include<iostream>
#include<iomanip>
using namespace std;
template<class T>
void output(T list[], int hi)
{
    int x,i=0;
    for (x = 0; x < hi; x++)
    {
        i++;
        cout <<setw(5)<< list[x] << " ";
        if (i % 6 == 0&&x!=hi-1)
            cout << endl;
    }
    cout <<endl;
}
#endif

 

Screensort；

 

3：用户类User

Code（测试）：

 

#include <iostream> 
#include <string> 
#include<cstdlib>
#include<conio.h>
using namespace std;
// User类的声明 
class User
{
public:
    void setInfo(string newn, string newp = "111111", string newe = "");
    void changePasswd();
    void printInfo();
    void changeemail();

private:
    string name;
    string passwd;
    string email;
};
//输入字符串，显示*
string enter()
{
    char ch;
    string outer;
    while ((ch = _getch())!='\r')
    {
        outer += ch;
        cout << "*";
    }
    cout << endl;
    return outer;
}
//初始化信息
void User::setInfo(string newn, string newp/*="111111"*/, string newe/*=""*/)
{
    name = newn;
    passwd = newp;
    email = newe;
}

//修改密码
void User::changePasswd()
{
    cout << "Enter the old passwd:";
    string outer;
    int jud = 1;
    outer = enter();
    while (outer != passwd)
    {
        cout << "Passwd input error,please re-enter again:";
        outer = enter();
        jud++;
        if (jud == 3)
            break;
    }
    if (outer != passwd)
        cout << "Please try after a while.\n";
    else
    {
        cout << "Please enter the new passwd:";
        passwd = enter();
        do
        {
            cout << "Please enter the new passwd again:";
            outer=enter();
            if (outer != passwd)
            {
                cout << "Passwd input error,please change the new passwd:";
                passwd = enter();
            }
            else
                break;
        } while (true);
        cout << "Finish changepasswd." << endl;
    }
}
//修改邮箱
void User::changeemail()
{
    string outer,ch;
    cout << "Enter the new email:";
    cin >> outer;
    int a,b,jud;
    do
    {
        jud = 0;
        b = outer.length();
        for (a = 0; a < b; a++)
            if (outer.substr(a, 1) == "@")
                jud++;
        if (jud == 0)
        {
            cout << "Wrong format,please enter again:";
            cin >> outer;
        }
        else
            cout << "Finish change email." << endl;
    } while (jud == 0);
    email = outer;
}
//打印至屏幕
void User::printInfo()
{
    int y,x = passwd.length();
    string outerx;
    for (y = 1; y <= x; y++)
        outerx += '*';
    cout << "name:" << name << endl;
    cout << "passwd:" << outerx<< endl;
    cout << "email:" << email << endl;
}
int main()
{
        cout << "testing 1......" << endl;
        // 测试1 
        User user1;
        user1.setInfo("Leonard");
        user1.printInfo();
        user1.changePasswd();
        user1.printInfo();
        cout << endl << "testing 2......" << endl << endl;
        // 测试2
        User user2;
        user2.setInfo("Jonny", "92197", "xyz@hotmail.com");
        user2.printInfo();
        system("pause");
    return 0;
}

 

Screensort：

 

功能完善

Code：

 

#include <iostream> 
#include <string> 
#include<cstdlib>
#include<conio.h>
using namespace std;
// User类的声明 
class User
{
public:
    void setInfo(string newn, string newp = "111111", string newe = "");
    void changePasswd();
    void printInfo();
    void changeemail();

private:
    string name;
    string passwd;
    string email;
};
//输入字符串，显示*
string enter()
{
    char ch;
    string outer;
    while ((ch = _getch())!='\r')
    {
        outer += ch;
        cout << "*";
    }
    cout << endl;
    return outer;
}
//初始化信息
void User::setInfo(string newn, string newp/*="111111"*/, string newe/*=""*/)
{
    name = newn;
    passwd = newp;
    email = newe;
}

//修改密码
void User::changePasswd()
{
    cout << "Enter the old passwd:";
    string outer;
    int jud = 1;
    outer = enter();
    while (outer != passwd)
    {
        cout << "Passwd input error,please re-enter again:";
        outer = enter();
        jud++;
        if (jud == 3)
            break;
    }
    if (outer != passwd)
        cout << "Please try after a while.\n";
    else
    {
        cout << "Please enter the new passwd:";
        passwd = enter();
        do
        {
            cout << "Please enter the new passwd again:";
            outer=enter();
            if (outer != passwd)
            {
                cout << "Passwd input error,please change the new passwd:";
                passwd = enter();
            }
            else
                break;
        } while (true);
        cout << "Finish changepasswd." << endl;
    }
}
//修改邮箱
void User::changeemail()
{
    string outer,ch;
    cout << "Enter the new email:";
    cin >> outer;
    int a,b,jud;
    do
    {
        jud = 0;
        b = outer.length();
        for (a = 0; a < b; a++)
            if (outer.substr(a, 1) == "@")
                jud++;
        if (jud == 0)
        {
            cout << "Wrong format,please enter again:";
            cin >> outer;
        }
        else
            cout << "Finish change email." << endl;
    } while (jud == 0);
    email = outer;
}
//打印至屏幕
void User::printInfo()
{
    int y,x = passwd.length();
    string outerx;
    for (y = 1; y <= x; y++)
        outerx += '*';
    cout << "name:" << name << endl;
    cout << "passwd:" << outerx<< endl;
    cout << "email:" << email << endl;
}
int main()
{
    User you;
    //输入用户名
    string name;
    cout << "Enter your name(password:111111):";
    cin >> name;
    you.setInfo(name);
    //操作列表
    cout << "Choose your operation" << endl;
    cout << "1--change password"<<endl;
    cout << "2-change email"<<endl;
    cout << "3-print on the screen" << endl;
    cout << "0-EXIT" << endl;
    int x=1;
    while (x!=0)
    {
        cout << "Your operation is:";
        cin >> x;
        switch (x)
        {
        case 1:
            you.changePasswd();
            continue;
        case 2:
            you.changeemail();
            continue;
        case 3:
            you.printInfo();
            continue;
        default:
            cout<<"Wrong operation,please enter again."<<endl;
        }
    }
    system("pause");
    return 0;
}

 

 

Screensort：

 

 

实验总结与体会

 

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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

评论地址：

https://www.cnblogs.com/laboratory-X/p/10590562.html

https://www.cnblogs.com/elise00/p/10589654.html

https://www.cnblogs.com/linjiahao1035/p/10585993.html