作业6
实验任务1
#pragma once
#include <iomanip>
#include <iostream>
#include <string>struct Contestant {long id; // 学号std::string name; // 姓名std::string major; // 专业int solved; // 解题数int penalty; // 总罚时
};// 重载<<
// 要求：姓名/专业里不含空白符
inline std::ostream& operator<<(std::ostream& out, const Contestant& c) {out << std::left;out << std::setw(15) << c.id<< std::setw(15) << c.name<< std::setw(15) << c.major<< std::setw(10) << c.solved<< std::setw(10) << c.penalty;return out;
}// 重载>>
inline std::istream& operator>>(std::istream& in, Contestant& c) {in >> c.id >> c.name >> c.major >> c.solved >> c.penalty;return in;
}```cpp```
#pragma once
#include <fstream>
#include <iostream>
#include <stdexcept>
#include <string>
#include <vector>
#include "contestant.hpp"// ACM 排序规则：先按解题数降序，再按罚时升序
inline bool cmp_by_solve(const Contestant& a, const Contestant& b) {if(a.solved != b.solved)return a.solved > b.solved;return a.penalty < b.penalty;
}// 将结果写至任意输出流
inline void write(std::ostream& os, const std::vector<Contestant>& v) {for (const auto& x : v) os << x << '\n';
}// 将结果打印到屏幕
inline void print(const std::vector<Contestant>& v) {write(std::cout, v);
}// 将结果保存到文件
inline void save(const std::string& filename, const std::vector<Contestant>& v) {std::ofstream os(filename);if (!os) throw std::runtime_error("fail to open " + filename);write(os, v);
}// 从文件读取信息（跳过标题行）
inline std::vector<Contestant> load(const std::string& filename) {std::ifstream is(filename);if (!is) throw std::runtime_error("fail to open " + filename);std::string line;std::getline(is, line); // 跳过标题std::vector<Contestant> v;Contestant t;int seq;while (is >> seq >> t) v.push_back(t);return v;
}```cpp```#include <algorithm>
#include <iostream>
#include <stdexcept>
#include <vector>
#include "contestant.hpp"
#include "utils.hpp"const std::string in_file = "./data_bad.txt";
const std::string out_file = "./ans.txt";void app() {std::vector<Contestant> contestants;try {contestants = load(in_file); std::sort(contestants.begin(), contestants.end(), cmp_by_solve); print(contestants); save(out_file, contestants); } catch (const std::exception& e) {std::cerr << e.what() << '\n';return;}
}int main() {app();
}```cpp问题1.1. 因为std::ostream 是他们的基类2. 不需要问题2.1.在输入文件和输出文件无法打开的时候会被抛出2. 会被app里的catch捕获，然后他会打印抛出的内容问题3.可以，结果都是一致的问题4.1.Thomas的数据出现异常，他之后的数据没有被处理, 因为Thomas有未给出的数据，程序把下一行的开头内容作为Thomas数据的一部分2.按行读取文件，先读取一行的数据，在处理单行时发现异常跳过该行并输出异常，无异常的话push_back;### 试验任务2```#pragma once#include <iostream>
#include <string>class Student {
public:Student() = default;~Student() = default;const std::string get_major() const;int get_grade() const;friend std::ostream& operator<<(std::ostream& os, const Student& s);friend std::istream& operator>>(std::istream& is, Student& s);private:int id; std::string name;std::string major;int grade; // 0-100
};``````cpp#pragma once
#include <string>
#include <vector>
#include "student.hpp"class StuMgr {
public:void load(const std::string& file); // 加载数据文件（空格分隔）void sort(); // 排序: 按专业字典序升序、同专业分数降序void print() const; // 打印到屏幕void save(const std::string& file) const; // 保存到文件private:void write(std::ostream &os) const; // 把数据写到任意输出流private:std::vector<Student> students;
};```cpp```#include <exception>
#include <iostream>
#include <limits>
#include <string>
#include "stumgr.hpp"const std::string in_file = "./data.txt";
const std::string out_file = "./ans.txt";void menu() {std::cout << "\n**********简易应用**********\n""1. 加载文件\n""2. 排序\n""3. 打印到屏幕\n""4. 保存到文件\n""5. 退出\n""请选择：";
}void app() {StuMgr mgr;int choice = 0;while(true) {menu();std::cin >> choice;try {switch (choice) {case 1: mgr.load(in_file); std::cout << "加载成功\n"; break;case 2: mgr.sort(); std::cout << "排序已完成\n"; break;case 3: mgr.print(); std::cout << "打印已完成\n"; break;case 4: mgr.save(out_file); std::cout << "导出成功\n"; break;case 5: return;default: std::cout << "不合法输入\n";}}catch (const std::exception& e) {std::cout << "Error: " << e.what() << '\n';}}
}int main() {app();
}```cpp```#include "student.hpp"const std::string Student::get_major() const {return major;}int Student::get_grade() const {return grade;}std::ostream& operator<<(std::ostream& os, const Student& s) {os << s.id << " " << s.name << " " << s.major << " " << s.grade << std::endl;return os;}std::istream& operator>>(std::istream& is, Student& s) {if(!(is >> s.id >> s.name >> s.major >> s.grade)) {throw std::runtime_error("line is error");}return is;}``````cpp#include "stumgr.hpp"#include "student.hpp"#include <fstream>#include <istream>#include <sstream>#include <stdexcept>#include <string>#include <algorithm>void StuMgr::load(const std::string& file){std::ifstream fs(file);if(!fs) throw std::runtime_error("ERROR: input file can not to open");std::string line; int line_count = 0;Student s; std::getline(fs,line);while(std::getline(fs,line)) {line_count++;std::istringstream is(line);try{is >> s;students.push_back(s);}catch(std::exception& e) {std::cerr << line_count << e.what() << std::endl;}is.clear();}} // 加载数据文件（空格分隔）void StuMgr::sort() {std::sort(students.begin(),students.end(), [&](Student& a, Student& b) {if(a.get_major() < b.get_major()) {return true;}else if (a.get_major() == b.get_major()) {return a.get_grade() < b.get_grade();}return false;});} // 排序: 按专业字典序升序、同专业分数降序void StuMgr::print() const {for(auto& student: students) {std::cout << student << std::endl;}} // 打印到屏幕void StuMgr::save(const std::string& file) const {std::ofstream os(file);write(os);} // 保存到文件void StuMgr::write(std::ostream &os) const {for(auto& student: students) {os << student;}} // 把数据写到任意输出流```cpp| | | |
| ---- | ---- | ---- |
| | | |
