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;
}
#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;
}
#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();
}
![0c750d25627d76590e2e739c6d0e44e8]()
![57d3cb2b99200305c9298f3d17b99e60]()
问题1.
1. 因为std::ostream 是他们的基类
2. 不需要
![06731f2550415d2e52adeb7194dc7f12]()
![23931618aa1106384641bc46b35b6c24]()
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.
![d4a672d0d4425bd302163d5b040ac827]()
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;
};
#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();
}
#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;
}
```
```cppp
#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
![fcd4f63705909c2fbd74ba7bea76f24e]()
![85aa51d9343c113a190f063fc9bee2ec]()
![57d3cb2b99200305c9298f3d17b99e60]()
![0c750d25627d76590e2e739c6d0e44e8]()
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