实验4

GradeCalc.hpp

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <numeric>
#include <iomanip>

using std::vector;
using std::string;
using std::cin;
using std::cout;
using std::endl;

class GradeCalc: public vector<int> {
public:
    GradeCalc(const string &cname, int size);      
    void input();                             // 录入成绩
    void output() const;                      // 输出成绩
    void sort(bool ascending = false);        // 排序 (默认降序)
    int min() const;                          // 返回最低分
    int max() const;                          // 返回最高分
    float average() const;                    // 返回平均分
    void info();                              // 输出课程成绩信息 

private:
    void compute();     // 成绩统计

private:
    string course_name;     // 课程名
    int n;                  // 课程人数
    vector<int> counts = vector<int>(5, 0);      // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]
    vector<double> rates = vector<double>(5, 0); // 保存各分数段比例 
};

GradeCalc::GradeCalc(const string &cname, int size): course_name{cname}, n{size} {}   

void GradeCalc::input() {
    int grade;

    for(int i = 0; i < n; ++i) {
        cin >> grade;
        this->push_back(grade);
    } 
}  

void GradeCalc::output() const {
    for(auto ptr = this->begin(); ptr != this->end(); ++ptr)
        cout << *ptr << " ";
    cout << endl;
} 

void GradeCalc::sort(bool ascending) {
    if(ascending)
        std::sort(this->begin(), this->end());
    else
        std::sort(this->begin(), this->end(), std::greater<int>());
}  

int GradeCalc::min() const {
    return *std::min_element(this->begin(), this->end());
}  

int GradeCalc::max() const {
    return *std::max_element(this->begin(), this->end());
}    

float GradeCalc::average() const {
    return std::accumulate(this->begin(), this->end(), 0) * 1.0 / n;
}   

void GradeCalc::compute() {
    for(int grade: *this) {
        if(grade < 60)
            counts.at(0)++;
        else if(grade >= 60 && grade < 70)
            counts.at(1)++;
        else if(grade >= 70 && grade < 80)
            counts.at(2)++;
        else if(grade >= 80 && grade < 90)
            counts.at(3)++;
        else if(grade >= 90)
            counts.at(4)++;
    }

    for(int i = 0; i < rates.size(); ++i)
        rates.at(i) = counts.at(i) * 1.0 / n;
}

void GradeCalc::info()  {
    cout << "课程名称:\t" << course_name << endl;
    cout << "排序后成绩: \t";
    sort();  output();
    cout << "最高分:\t" << max() << endl;
    cout << "最低分:\t" << min() << endl;
    cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
    
    compute();  // 统计各分数段人数、比例

    vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
    for(int i = tmp.size()-1; i >= 0; --i)
        cout << tmp[i] << "\t: " << counts[i] << "人\t" 
             << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl; 
} 

demo2.cpp

#include "GradeCalc.hpp"
#include <iomanip>

void test() {
    int n;
    cout << "输入班级人数: ";
    cin >> n;

    GradeCalc c1("OOP", n);

    cout << "录入成绩: " << endl;;
    c1.input();
    cout << "输出成绩: " << endl;
    c1.output();

    cout << string(20, '*') + "课程成绩信息"  + string(20, '*') << endl;
    c1.info();
}

int main() {
    test();
}

在基类vector<int>里

this指针

从头加到尾乘1.0再除以n求平均值。有。让运算结果变为浮点型 ，可以有小数。

GradeCalc.hpp

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <numeric>
#include <iomanip>

using std::vector;
using std::string;
using std::cin;
using std::cout;
using std::endl;

class GradeCalc {
public:
    GradeCalc(const string &cname, int size);      
    void input();                             // 录入成绩
    void output() const;                      // 输出成绩
    void sort(bool ascending = false);        // 排序 (默认降序)
    int min() const;                          // 返回最低分
    int max() const;                          // 返回最高分
    float average() const;                    // 返回平均分
    void info();                              // 输出课程成绩信息 

private:
    void compute();     // 成绩统计

private:
    string course_name;     // 课程名
    int n;                  // 课程人数
    vector<int> grades;     // 课程成绩
    vector<int> counts = vector<int>(5, 0);      // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]
    vector<double> rates = vector<double>(5, 0); // 保存各分数段比例 
};

GradeCalc::GradeCalc(const string &cname, int size): course_name{cname}, n{size} {}   

void GradeCalc::input() {
    int grade;

    for(int i = 0; i < n; ++i) {
        cin >> grade;
        grades.push_back(grade);
    } 
}  

void GradeCalc::output() const {
    for(int grade: grades)
        cout << grade << " ";
    cout << endl;
} 

void GradeCalc::sort(bool ascending) {
    if(ascending)
        std::sort(grades.begin(), grades.end());
    else
        std::sort(grades.begin(), grades.end(), std::greater<int>());
        
}  

int GradeCalc::min() const {
    return *std::min_element(grades.begin(), grades.end());
}  

int GradeCalc::max() const {
    return *std::max_element(grades.begin(), grades.end());
}    

float GradeCalc::average() const {
    return std::accumulate(grades.begin(), grades.end(), 0) * 1.0 / n;
}   

void GradeCalc::compute() {
    for(int grade: grades) {
        if(grade < 60)
            counts.at(0)++;
        else if(grade >= 60 && grade < 70)
            counts.at(1)++;
        else if(grade >= 70 && grade < 80)
            counts.at(2)++;
        else if(grade >= 80 && grade < 90)
            counts.at(3)++;
        else if(grade >= 90)
            counts.at(4)++;
    }

    for(int i = 0; i < rates.size(); ++i)
        rates.at(i) = counts.at(i) *1.0 / n;
}

void GradeCalc::info()  {
    cout << "课程名称:\t" << course_name << endl;
    cout << "排序后成绩: \t";
    sort();  output();
    cout << "最高分:\t" << max() << endl;
    cout << "最低分:\t" << min() << endl;
    cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
    
    compute();  // 统计各分数段人数、比例

    vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
    for(int i = tmp.size()-1; i >= 0; --i)
        cout << tmp[i] << "\t: " << counts[i] << "人\t" 
             << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl; 
} 

demo3.cpp

#include "GradeCalc.hpp"
#include <iomanip>

void test() {
    int n;
    cout << "输入班级人数: ";
    cin >> n;

    GradeCalc c1("OOP", n);

    cout << "录入成绩: " << endl;;
    c1.input();
    cout << "输出成绩: " << endl;
    c1.output();

    cout << string(20, '*') + "课程成绩信息"  + string(20, '*') << endl;
    c1.info();
}

int main() {
    test();
}

vector<int> grades里。直接使用grade的vectory函数。

task4_1

#include <iostream>
#include <string>
#include <limits>

using namespace std;

void test1() {
    string s1, s2;
    cin >> s1 >> s2;  // cin: 从输入流读取字符串, 碰到空白符(空格/回车/Tab)即结束
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

void test2() {
    string s1, s2;
    getline(cin, s1);  // getline(): 从输入流中提取字符串，直到遇到换行符
    getline(cin, s2);
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

void test3() {
    string s1, s2;
    getline(cin, s1, ' '); //从输入流中提取字符串，直到遇到指定分隔符
    getline(cin, s2);
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

int main() {
    cout << "测试1: 使用标准输入流对象cin输入字符串" << endl;
    test1();
    cout << endl;

    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    cout << "测试2: 使用函数getline()输入字符串" << endl;
    test2();
    cout << endl;

    cout << "测试3: 使用函数getline()输入字符串, 指定字符串分隔符" << endl;
    test3();
}

防止test1输入末尾的 '\n' 被getline错误录入

task4_2

#include <iostream>
#include <string>
#include <vector>
#include <limits>

using namespace std;

void output(const vector<string> &v) {
    for(auto &s: v)
        cout << s << endl;
}

void test() {
    int n;
    while(cout << "Enter n: ", cin >> n) {
        vector<string> v1;

        for(int i = 0; i < n; ++i) {
            string s;
            cin >> s;
            v1.push_back(s);
        }

        cout << "output v1: " << endl;
        output(v1); 
        cout << endl;
    }
}

int main() {
    cout << "测试: 使用cin多组输入字符串" << endl;
    test();
}

task4_2

#include <iostream>
#include <string>
#include <vector>
#include <limits>

using namespace std;

void output(const vector<string> &v) {
    for(auto &s: v)
        cout << s << endl;
}

void test() {
    int n;
    while(cout << "Enter n: ", cin >> n) {
        cin.ignore(numeric_limits<streamsize>::max(), '\n');

        vector<string> v2;

        for(int i = 0; i < n; ++i) {
            string s;
            getline(cin, s);
            v2.push_back(s);
        }
        cout << "output v2: " << endl;
        output(v2); 
        cout << endl;
    }
}

int main() {
    cout << "测试: 使用函数getline()多组输入字符串" << endl;
    test();
}

防止各种输入末尾的 '\n' 被getline错误录入

grm.hpp

#include <iostream>

using std::cout;
using std::endl;

template<typename T>
class GameResourceManager
{
    private:
        T resource;
    public:
        GameResourceManager(T n);
        T get();
        void update(T i);
};

template<typename T>
GameResourceManager<T>::GameResourceManager(T n): resource{n} {}

template<typename T>
T GameResourceManager<T>::get() { return resource; }

template<typename T>
void GameResourceManager<T>::update(T i)
{
    if(resource+i<0)
            resource=0;
    else
        resource += i;
}

task5.cpp

#include "grm.hpp"
#include <iostream>

using std::cout;
using std::endl;

void test1() {
    GameResourceManager<float> HP_manager(99.99);
    cout << "当前生命值: " << HP_manager.get() << endl;
    HP_manager.update(9.99);
    cout << "增加9.99生命值后, 当前生命值: " << HP_manager.get() << endl;
    HP_manager.update(-999.99);
    cout <<"减少999.99生命值后, 当前生命值: " << HP_manager.get() << endl;
}

void test2() {
    GameResourceManager<int> Gold_manager(100);
    cout << "当前金币数量: " << Gold_manager.get() << endl;
    Gold_manager.update(50);
    cout << "增加50个金币后, 当前金币数量: " << Gold_manager.get() << endl;
    Gold_manager.update(-99);
    cout <<"减少99个金币后, 当前金币数量: " << Gold_manager.get() << endl;
}


int main() {
    cout << "测试1: 用float类型对类模板GameResourceManager实例化" << endl;
    test1();
    cout << endl;

    cout << "测试2: 用int类型对类模板GameResourceManager实例化" << endl;
    test2();
}

 task6

info.hpp

#include <string>
#include <iostream>
#include <iomanip>

using namespace std;
using std::string;

class info
{
    private:
        string name;
        string contact;
        string city;
        int n;
        
    public:
        static int total;
        
        info(string NAM="NU*LL",string CON="NU*LL",string CIT="NU*LL",int N=0);
        void display();
};

int info::total=0;
info::info(string NAM,string CON,string CIT,int N): name{NAM},contact{CON},city{CIT},n{N} { total+=n; }
void info::display(){
    cout << setw(20) << "昵称："
         << name << endl;
    cout << setw(20) << "联系方式："
         << contact << endl;
    cout << setw(20) << "所在城市："
         << city << endl;
    cout << setw(20) << "预定人数："
         << n << endl;
    cout << "-----------------------------------------------------" <<endl;
}

demo6.cpp

#include <string>
#include <iostream>
#include <iomanip>
#include <vector>
#include "info.hpp"

using namespace std;
using std::string;

int main()
{
    const int max = 100;
    cout << "录入预约信息：" << endl;
    cout << endl;
    cout << left << setw(20) << "昵称"
                 << setw(35) << "联系方式(手机/邮箱)"
                 << setw(30) << "所在城市"
                 << setw(15) << "预定参加人数" << endl;
    
    int NUM;
    string A,B,C;
    vector<info> audience_lst;
    while( cin >> A >> B >> C >> NUM )
    {
        if( info::total+NUM > max )
        {
            int o = max-info::total;
            char choic; 
            cout << "对不起，只剩" << o << "个位置" << endl;
            cout << "输入u，更新预定信息" << endl;
            cout << "输入q，退出预定" << endl;
            cout << "你的选择:" << endl;
            cin >> choic;
            if(choic=='q')
                break;
            else if(choic=='u')
            {    cout << "请重新输入预定信息" << endl;    continue;   }
            else
            {    cout << "无效信息" << endl;      break;   }
        }
        else
        {
            info man(A,B,C,NUM);
            audience_lst.push_back(man);
            if( info::total == max )
                break;
        }
    }
    cout << "截至目前，共" << info::total << "名听众预约。预约听众信息如下" << endl;
    cout << "-----------------------------------------------------" <<endl; 
    for(auto i: audience_lst)
        i.display();
    cout << "-----------------------------------------------------" <<endl; 
}