C++程序设计学籍管理有错误
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;
// 学生类
class Student {
public:
string id; // 学号
string name; // 姓名
string gender; // 性别
string major; // 专业
string status; // 学籍状态
string hometown; // 籍贯
Student() {}
Student(string id, string name, string gender, string major, string status, string hometown) :
id(id), name(name), gender(gender), major(major), status(status), hometown(hometown) {}
};
// 成绩类
class Grade {
public:
string id; // 学号
string course; // 课程名称
double score; // 成绩
Grade() {}
Grade(string id, string course, double score) : id(id), course(course), score(score) {}
};
// 学生管理系统类
class StudentManagementSystem {
private:
vector<Student> students; // 学生信息
vector<Grade> grades; // 成绩信息
int max_id; // 每输入一个学生信息学号顺序加1
public:
StudentManagementSystem() : max_id(0) {}
~StudentManagementSystem() {}
// 打印菜单
void print_menu() {
cout << "===========================" << endl;
cout << "1.录入学生基本信息" << endl;
cout << "2.显示/修改/增加/删除学生信息" << endl;
cout << "3.学生基本情况查询" << endl;
cout << "4.学生成绩查询" << endl;
cout << "5.全部学生信息查询" << endl;
cout << "6.统计各专业的成绩，性别比例及籍贯" << endl;
cout << "7.保存学生信息和成绩信息" << endl;
cout << "0.退出程序" << endl;
cout << "===========================" << endl;
}
// 读取学生信息和成绩信息
void load_data() {
ifstream fin("students.txt");
if (fin.good()) {
string line;
while (getline(fin, line)) {
string id, name, gender, major, status, hometown;
istringstream iss(line);
iss >> id >> name >> gender >> major >> status >> hometown;
students.push_back(Student(id, name, gender, major, status, hometown));
max_id = max(max_id, stoi(id));
}
}
fin.close();
fin.open("grades.txt");
if (fin.good()) {
string line;
while (getline(fin, line)) {
string id, course;
double score;
istringstream iss(line);
iss >> id >> course >> score;
grades.push_back(Grade(id, course, score));
}
}
fin.close();
}
// 保存学生信息和成绩信息
void save_data() {
ofstream fout("students.txt");
for (const auto& s : students) {
fout << s.id << " " << s.name << " " << s.gender << " " << s.major << " " << s.status << " " << s.hometown << endl;
}
fout.close();
fout.open("grades.txt");
for (const auto& g : grades) {
fout << g.id << " " << g.course << " " << g.score << endl;
}
fout.close();
}
// 录入学生信息
void add_student() {
string name, gender, major, status, hometown;
cout << "请输入学生姓名：";
cin >> name;
cout << "请输入学生性别：";
cin >> gender;
cout << "请输入学生专业：";
cin >> major;
cout << "请输入学生学籍状态：";
cin >> status;
cout << "请输入学生籍贯：";
cin >> hometown;
max_id++;
students.push_back(Student(to_string(max_id), name, gender, major, status, hometown));
cout << "录入成功！" << endl;
}
// 显示, 修改, 增加, 删除学生信息
void manage_student() {
cout << "请输入操作编号（1.显示全部学生信息；2.修改学生信息；3.增加学生信息；4.删除学生信息；0.返回）：";
int choice;
cin >> choice;
if (choice == 0) {
return;
}
else if (choice == 1) {
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
for (const auto& s : students) {
cout << left << setw(4) << s.id << setw(10) << s.name << setw(6) << s.gender << setw(12) << s.major << setw(6) << s.status << setw(10) << s.hometown << endl;
}
}
else if (choice == 2) {
string id, name, gender, major, status, hometown;
cout << "请输入要修改的学生学号：";
cin >> id;
auto it = find_if(students.begin(), students.end(), [&](const Student& s) { return s.id == id; });
if (it != students.end()) {
cout << "当前学生信息：" << endl;
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
cout << left << setw(4) << it->id << setw(10) << it->name << setw(6) << it->gender << setw(12) << it->major << setw(6) << it->status << setw(10) << it->hometown << endl;
cout << "请输入修改后的学生姓名：";
cin >> name;
cout << "请输入修改后的学生性别：";
cin >> gender;
cout << "请输入修改后的学生专业：";
cin >> major;
cout << "请输入修改后的学生学籍状态：";
cin >> status;
cout << "请输入修改后的学生籍贯：";
cin >> hometown;
*it = Student(id, name, gender, major, status, hometown);
cout << "修改成功！" << endl;
}
else {
cout << "未找到该学生！" << endl;
}
}
else if (choice == 3) {
add_student();
}
else if (choice == 4) {
string id;
cout << "请输入要删除的学生学号：";
cin >> id;
auto it = find_if(students.begin(), students.end(), [&](const Student& s) { return s.id == id; });
if (it != students.end()) {
students.erase(it);
cout << "删除成功！" << endl;
}
else {
cout << "未找到该学生！" << endl;
}
}
else {
cout << "无效操作！" << endl;
}
}
// 学生基本情况查询
void search_student() {
cout << "请输入查询方式编号（1.查找学号；2.查找姓名；3.查找专业）：";
int choice;
cin >> choice;
string keyword;
if (choice == 1) {
cout << "请输入学号：";
cin >> keyword;
auto it = find_if(students.begin(), students.end(), [&](const Student& s) { return s.id == keyword; });
if (it != students.end()) {
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
cout << left << setw(4) << it->id << setw(10) << it->name << setw(6) << it->gender << setw(12) << it->major << setw(6) << it->status << setw(10) << it->hometown << endl;
}
else {
cout << "未找到该学生！" << endl;
}
}
else if (choice == 2) {
cout << "请输入姓名：";
cin >> keyword;
auto it = find_if(students.begin(), students.end(), [&](const Student& s) { return s.name == keyword; });
if (it != students.end()) {
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
cout << left << setw(4) << it->id << setw(10) << it->name << setw(6) << it->gender << setw(12) << it->major << setw(6) << it->status << setw(10) << it->hometown << endl;
}
else {
cout << "未找到该学生！" << endl;
}
}
else if (choice == 3) {
cout << "请输入专业：";
cin >> keyword;
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
for (const auto& s : students) {
if (s.major == keyword) {
cout << left << setw(4) << s.id << setw(10) << s.name << setw(6) << s.gender << setw(12) << s.major << setw(6) << s.status << setw(10) << s.hometown << endl;
}
}
}
else {
cout << "无效操作！" << endl;
}
}
// 学生成绩查询
void search_grade() {
string id;
cout << "请输入学生学号：";
cin >> id;
auto it = find_if(students.begin(), students.end(), [&](const Student& s) { return s.id == id; });
if (it == students.end()) {
cout << "未找到该学生！" << endl;
return;
}
cout << "当前学生成绩信息：" << endl;
cout << left << setw(10) << "课程名称" << setw(6) << "成绩" << endl;
bool found = false;
for (const auto& g : grades) {
if (g.id == id) {
cout << left << setw(10) << g.course << setw(6) << g.score << endl;
found = true;
}
}
if (!found) {
cout << "无成绩信息！" << endl;
}
}
// 全部学生信息查询
void search_all_students() {
cout << left << setw(4) << "学号" << setw(10) << "姓名" << setw(6) << "性别" << setw(12) << "专业" << setw(6) << "状态" << setw(10) << "籍贯" << endl;
for (const auto& s : students) {
cout << left << setw(4) << s.id << setw(10) << s.name << setw(6) << s.gender << setw(12) << s.major << setw(6) << s.status << setw(10) << s.hometown << endl;
}
}
// 统计各专业的成绩，性别比例及籍贯
void stat() {
cout << left << setw(12) << "专业" << setw(10) << "平均成绩" << setw(10) << "女生比例" << setw(10) << "籍贯" << endl;
for (const auto& s : students) {
auto it = find_if(grades.begin(), grades.end(), [&](const Grade& g) { return g.id == s.id; });
if (it != grades.end()) {
double sum = 0;
int count = 0;
for (const auto& g : grades) {
if (g.id == s.id) {
sum += g.score;
count++;
}
}
double avg_score = sum / count;
int female_count = count_if(students.begin(), students.end(), [&](const Student& x) { return x.major == s.major && x.gender == "女"; });
vector<string> hometowns;
for (const auto& x : students) {
if (x.major == s.major) {
hometowns.push_back(x.hometown);
}
}
sort(hometowns.begin(), hometowns.end());
auto it = unique(hometowns.begin(), hometowns.end());
hometowns.erase(it, hometowns.end());
cout << left << setw(12) << s.major << setw(10) << fixed << setprecision(2) << avg_score << setw(10) << fixed << setprecision(0) << (double)female_count / count << setw(10);
for (int i = 0; i < (int)hometowns.size(); i++) {
if (i > 0) {
cout << ",";
}
cout << hometowns[i];
}
cout << endl;
}
}
}
};
int main() {
StudentManagementSystem system;
system.load_data();
while (true) {
system.print_menu();
cout << "请输入操作编号：";
int choice;
cin >> choice;
switch (choice) {
case 0:
system.save_data();
cout << "程序已退出！" << endl;
return 0;
case 1:
system.add_student();
break;
case 2:
system.manage_student();
break;
case 3:
system.search_student();
break;
case 4:
system.search_grade();
break;
case 5:
system.search_all_students();
break;
case 6:
system.stat();
break;
case 7:
system.save_data();
cout << "已保存学生信息和成绩信息！" << endl;
break;
default:
cout << "无效操作！" << endl;
break;
}
}
}
为什么还是有错误，打了好久了。
- 你可以参考下这个问题的回答, 看看是否对你有帮助, 链接: https://ask.csdn.net/questions/7700388
- 这篇博客也不错, 你可以看下C++简单学生管理程序【实现输出成绩，查找学号等】
- 除此之外, 这篇博客: C++程序设计基础知识学习中的 算数运算符于表达式： 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
基本算术运算符：
- float型数据运算时会转化为double型
- int型运算时有时采用“向零取整”，有时采用“向下取整”
int i = -5/3; //向零取整 i = -1; //向下取整 i = -2;运算符之间的优先等级：（优先级越低优先度越高，仅列出部分运算符）
优先级 运算符 结合方向 2 () [] -> . ++（后置时） --（后置时） 自左向右 3 ++（前置时） --（前置时） ! -（做符号时） +（做符号时） *（指针） &（取址） (类型)（类型转换） sizeof new delete 自右向左 4 * / % 自左向右 5 + - 自左向右 6 <<（左位移运算） >>（右位移运算） 自左向右 7 < <= >= > 自左向右 8 == != 自左向右 混合数据类型运算时数据类型的处理：有符号转无符号，short转long，char转int，int转double，float转double（float参与运算时自动转double）
例：int i; char c; float f; double d; //省略赋值细节 ... 10 + 'a' + i * f - d //先计算10 + 'a' 此时将char型字符'a'转为int型整数 //再计算i * f，由于int型和float型混合运算，float型运算时转为double型，因此结果为double型 //综上为：int + char + int * float(double) - double = double //下列两式之间等价 x % = y + 8; x = x % (y + 8); //下式最后a的值为60 a = 3 * 5 , a * 4- 您还可以看一下 王健伟老师的C++语言基础到进阶课程中的 模板概念，函数模板定义、调用小节, 巩固相关知识点