实验6 模板类、文件I/O和异常处理
任务一
Complex.hpp
#pragma once #include <iostream> #include <stdexcept> // 声明 //////////////////////////////////////////////////// // 复数模板类声明 template<typename T> class Complex { public: Complex(T r = 0, T i = 0); Complex(const Complex<T> &c); T get_real() const; T get_imag() const; // 重载+=为成员函数 Complex<T>& operator+=(const Complex<T> &c); // 重载<<、>>为友元函数 template<typename T1> friend std::ostream& operator<<(std::ostream &out, const Complex<T1> &c); template<typename T1> friend std::istream& operator>>(std::istream &in, Complex<T1> &c); private: T real, imag; }; // 普通函数声明 // 重载+用于Complex类型 template<typename T> Complex<T> operator+(const Complex<T> &c1, const Complex<T> &c2); // 重载==用于Complex类型 template<typename T> bool operator==(const Complex<T> &c1, const Complex<T> &c2); // 实现 //////////////////////////////////////////////////// // 成员函数模板实现 template<typename T> Complex<T>::Complex(T r, T i): real{r}, imag{i} { } template<typename T> Complex<T>::Complex(const Complex<T> &c): real{c.real}, imag{c.imag} { } template<typename T> T Complex<T>::get_real() const { return real; } template<typename T> T Complex<T>::get_imag() const { return imag; } // 重载+=为成员函数 template<typename T> Complex<T>& Complex<T>::operator+=(const Complex<T> &c) { real += c.real; imag += c.imag; return *this; } /////////////////////////////////////// // 友元函数模板实现 template<typename T1> std::ostream& operator<<(std::ostream &out, const Complex<T1> &c) { if(c.imag >= 0) out << c.real << " + " << c.imag << "i"; else out << c.real << " - " << -c.imag << "i"; return out; } template<typename T1> std::istream& operator>>(std::istream &in, Complex<T1> &c) { in >> c.real >> c.imag; return in; } /////////////////////////////////////// // 普通函数模板实现 // 重载+用于Complex类型 template<typename T> Complex<T> operator+(const Complex<T> &c1, const Complex<T> &c2) { return Complex<T>(c1.get_real()+c2.get_real(), c1.get_imag()+c2.get_imag()); } // 重载==用于Complex类型 template<typename T> bool operator==(const Complex<T> &c1, const Complex<T> &c2) { return c1.get_real() == c2.get_real() && c1.get_imag() && c2.get_imag(); }
task1.cpp
#include "Complex.hpp" #include <iostream> #include <fstream> #include <stdexcept> void test1(); void test2(); int main() { using namespace std; cout << "测试1: 复数模板类测试" << endl; test1(); cout << "\n测试2: 文件I/O测试" << endl; test2(); } void test1() { using namespace std; Complex<double> c1{3.5, 2}, c2; cout << "Enter c2: "; cin >> c2; cout << "c1 = " << c1 << endl; cout << "c2 = " << c2 << endl; cout << "c1 == c2: " << boolalpha << (c1 == c2) << endl; cout << "c1 + c2 = " << c1 + c2 << endl; c1 += c2; cout << "c1.real = " << c1.get_real() << endl; cout << "c1.imag = " << c1.get_imag() << endl; cout << "c1 == c2: " << boolalpha << (c1 == c2) << endl; } void test2() { using namespace std; Complex<int> c1{1, 2}, c2{9, -7}; ofstream out("ans.txt"); if(!out.is_open()) { cout << "fail to open file ans.txt to write\n"; return; } out << "c1 = " << c1 << endl; out << "c2 = " << c2 << endl; out << "c1 + c2 = " << c1 + c2 << endl; out << "(c1 == c2) = " << boolalpha << (c1 == c2) << endl; out.close(); cout << "测试ok!" << endl; }
运行结果截图
任务二
Contestant.hpp
#pragma once #include <iostream> #include <iomanip> #include <string> using std::string; using std::ostream; using std::istream; using std::setw; using std::setprecision; using std::setiosflags; using std::ios_base; // Contestant类声明 class Contestant { public: Contestant() = default; ~Contestant() = default; int get_num() const { return num; } float get_time_usage() const { return time_usage; } friend ostream& operator<<(ostream &out, const Contestant &c); friend istream& operator>>(istream &in, Contestant &c); private: string no; // 学号 string name; // 姓名 string major; // 专业 int num; // 解题数 float time_usage; // 总用时 }; // 友元函数实现 // 重载流插入运算符<< ostream& operator<<(ostream &out, const Contestant &c) { out << setiosflags(ios_base::left); out << setw(15) << c.no << setw(15) << c.name << setw(15) << c.major << setw(5) << c.num << setprecision(2) << c.time_usage; return out; } // 重载流提取运算符>> istream& operator>>(istream &in, Contestant &c) { in >> c.no >> c.name >> c.major >> c.num >> c.time_usage; return in; }
utils.hpp
#include "Contestant.hpp" #include <fstream> #include <iostream> #include <string> #include <vector> // 排序函数 // 按解题数比较，解题数相同的情况下，按总用时比较，总用时越少，排名越靠前 bool compare_by_solutionInfo(const Contestant &c1, const Contestant &c2) { if(c1.get_num() > c2.get_num()) return true; if(c1.get_num() == c2.get_num()) return c1.get_time_usage() < c2.get_time_usage(); return false; } // 把vector<Constestant>对象中的元素插入到输出流out void output(std::ostream &out, const std::vector<Contestant> &v) { for(auto &i: v) out << i << std::endl; } // 把vector<Contestant>对象中的元素写到filename文件中 void save(const std::string &filename, std::vector<Contestant> &v) { using std::ofstream; ofstream out(filename); if(!out.is_open()) { std::cout << "fail to open file to write\n"; return; } output(out, v); out.close(); } // 从文件filename读取参赛选手信息到vector<Contestant>对象 void load(const std::string &filename, std::vector<Contestant> &v) { using std::ifstream; ifstream in(filename); if(!in.is_open()) { std::cout << "fail to open file to read\n"; return; } std::string title_line; getline(in, title_line); // 跳过标题行 int first_column; Contestant t; while(in >> first_column >> t) v.push_back(t); in.close(); }
task2.cpp
#include "Contestant.hpp" #include "utils.hpp" #include <iostream> #include <vector> #include <algorithm> void test() { using namespace std; vector<Contestant> v; load("data2.txt", v); // 从文件加载选手信息到对象v sort(v.begin(), v.end(), compare_by_solutionInfo); // 按解题情况排序 output(cout, v); // 输出对象v中信息到屏幕 save("ans.txt", v); // 把对象v中选手信息保存到文件 } int main() { test(); }
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任务三
Triangle.hpp
#include <iostream> #include <stdexcept> #include <cmath> using namespace std; class Triangle { public: Triangle(double s1, double s2, double s3); ~Triangle() = default; double area() const; private: double a, b, c; }; Triangle::Triangle(double s1, double s2, double s3): a{s1}, b{s2}, c{s3} { if(a <= 0 || b <= 0 || c <= 0) throw invalid_argument("边长出现负值"); if(a+b <= c || b+c <= a || a+c <= b) throw invalid_argument("不满足任意两边之和大于第三边"); } double Triangle::area() const { double s = (a + b + c)/2; return sqrt(s*(s-a)*(s-b)*(s-c)); }
task3.cpp
#include "Triangle.hpp" #include <iostream> #include <fstream> void test() { using namespace std; cout << "从文件读入三角形三边边长，计算面积" << endl; ifstream in("data3.txt"); if(!in.is_open()) { cout << "fail to open file to read\n"; return; } double a,b,c; do { cout << "三角形边长: "; in >> a >> b >> c; cout << a << " " << b << " " << c << endl; try { Triangle t(a, b, c); cout << "三角形面积: " << t.area() << endl << endl; }catch(const exception &e) { cout << "error: " << e.what() << endl << endl; } if(in.peek() == EOF) break; } while(1); in.close(); } int main() { test(); }
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任务四
Vector.hpp
#pragma once #include<iostream> #include<stdexcept> using namespace std; template<typename T> class Vector{ private: int size; T *ptr; public: Vector(int s):size(s){ if(s<0) throw length_error("Vector constructor:negative size"); else ptr=new T[size]; } Vector(int s,T value):size(s){ if(s<0) throw length_error("Vector constructor:negative size"); else { ptr=new T[size]; for(int i=0;i<s;i++) *(ptr+i)=value; } } Vector(const Vector<T> &v){ size=v.size; ptr=new T[size]; for(int i=0;i<size;i++) *(ptr+i)=v.ptr[i]; } ~Vector(){delete []ptr;} int get_size(); T& at(int index); T& operator[](int index); friend void output(Vector<T> v){ for(int i=0;i<v.size;i++) cout<<v.ptr[i]<<"，"; cout<<endl; } }; template<typename T> int Vector<T>::get_size(){return size;} template<typename T> T& Vector<T>::at(int index){ if (index<0||index>=size) throw out_of_range("Vector:index out of range"); return *(ptr+index); } template<typename T> T& Vector<T>::operator[](int index){ if (index<0||index>=size) throw out_of_range("Vector:index out of range"); return *(ptr+index); }
task4.cpp
#include <iostream> #include "Vector.hpp" void test1() { using namespace std; int n; cout << "Enter n: "; cin >> n; Vector<double> x1(n); for(auto i = 0; i < n; ++i) x1.at(i) = i * 0.7; cout << "x1: "; output(x1); Vector<int> x2(n, 42); const Vector<int> x3(x2); cout << "x2: "; output(x2); cout << "x3: "; output(x3); x2.at(0) = 77; x2.at(1) = 777; cout << "x2: "; output(x2); cout << "x3: "; output(x3); } void test2() { using namespace std; int n, index; while(cout << "Enter n and index: ", cin >> n >> index) { try { Vector<int> v(n, n); v.at(index) = -999; cout << "v: "; output(v); } catch (const exception &e) { cout << e.what() << endl; } } } int main() { cout << "测试1: 模板类接口测试\n"; test1(); cout << "\n测试2: 模板类异常处理测试\n"; test2(); }
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任务五
#include <iostream> #include <fstream> #include <sstream> #include <vector> #include <algorithm> #include <string> struct Student { std::string id; std::string name; std::string major; int score; // 用于排序的比较函数 bool operator<(const Student& other) const { if (major != other.major) { return major < other.major; } else { return score > other.score; } } }; std::vector<Student> readStudentsFromFile(const std::string& filename) { std::vector<Student> students; std::ifstream file(filename); std::string line; std::getline(file, line); while (std::getline(file, line)) { std::istringstream iss(line); Student student; iss >> student.id >> student.name >> student.major >> student.score; students.push_back(student); } file.close(); return students; } void writeStudentsToFile(const std::vector<Student>& students, const std::string& filename) { std::ofstream file(filename); for (const auto& student : students) { file << student.id << "\t" << student.name << "\t" << student.major << "\t" << student.score << std::endl; } file.close(); } int main() { std::vector<Student> students = readStudentsFromFile("data5.txt"); std::sort(students.begin(), students.end()); std::cout << "学号\t姓名\t专业\t分数" << std::endl; for (const auto& student : students) { std::cout << student.id << "\t" << student.name << "\t" << student.major << "\t" << student.score << std::endl; } writeStudentsToFile(students, "ans5.txt"); return 0; }
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