void deleteStudent() { string idToDelete; cout << "请输入要删除的学生的学号:"; cin >> idToDelete; bool found = false; for (int i = 0; i < numStudents; i++) { if (students[i].id == idToDelete) { found = true; for (int j = i; j < numStudents - 1; j++) { students[j] = students[j + 1]; } numStudents--; cout << "删除成功!\n"; break; } } if (!found) { cout << "未找到该学生记录!\n"; } }解释这段代码
时间: 2024-01-27 22:06:14 浏览: 28
这段代码实现了一个从学生记录中删除指定学生信息的函数。首先,代码提示用户输入要删除的学生的学号,将其存储在字符串变量idToDelete中。
接下来,代码通过一个循环遍历学生记录中的学生信息,查找与idToDelete相同的学生。如果找到了相应学生,则将found标记为true,执行一个内嵌循环,将该学生后面的所有学生信息向前移动一位,然后将学生记录中的学生数量numStudents减1。最后,输出删除成功的提示信息,并使用break语句跳出循环。
如果未找到相应学生,则输出未找到该学生记录的提示信息。
相关问题
帮我用c++写一个程序:学生成绩管理系统,并实现以下要求: 定义学生(student)类,其中包括姓名、性别、学号、班级和语文数学英语物理学科的成绩。 设计菜单实现功能选择; 输入功能:输入学生信息,并以txt格式保存到文件中; 计算每个学生的总分与平均分的功能, 按照学生的每一科的功课成绩排序的功能。 按照学生的总成绩排序的功能。 学号修改学生信息的功能; 根据学号删除学生信息的功能; 查询功能: 能够根据学号查询学生信息; 能够根据姓名、班级查询学生信息; 统计学生成绩,按照班级和科目计算平均分。 所有的增加、修改、删除能同步到txt文件;也从txt文件读取数据到程序。
以下是基于C++的学生成绩管理系统的程序代码,包含了您提供的所有功能要求:
```c++
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
// 定义学生类
class Student {
public:
string name;
char gender;
string id;
string cls;
int chinese;
int math;
int english;
int physics;
int total_score;
// 构造函数
Student(string name, char gender, string id, string cls, int chinese, int math, int english, int physics) {
this->name = name;
this->gender = gender;
this->id = id;
this->cls = cls;
this->chinese = chinese;
this->math = math;
this->english = english;
this->physics = physics;
this->total_score = chinese + math + english + physics;
}
// 重载小于运算符,用于排序
bool operator < (const Student& st) const {
return total_score < st.total_score;
}
// 输出学生信息
void display() {
cout << setw(10) << name << setw(5) << gender << setw(15) << id << setw(10) << cls;
cout << setw(5) << chinese << setw(5) << math << setw(5) << english << setw(5) << physics;
cout << setw(5) << total_score << endl;
}
};
// 学生信息管理类
class StudentManager {
private:
vector<Student> students;
// 从文件中读取学生信息
void readFromFile() {
ifstream in("students.txt");
if (!in) return;
string name, id, cls;
char gender;
int chinese, math, english, physics;
while (in >> name >> gender >> id >> cls >> chinese >> math >> english >> physics) {
students.push_back(Student(name, gender, id, cls, chinese, math, english, physics));
}
in.close();
}
// 将学生信息写入文件
void writeToFile() {
ofstream out("students.txt");
for (auto& st : students) {
out << st.name << " " << st.gender << " " << st.id << " " << st.cls << " ";
out << st.chinese << " " << st.math << " " << st.english << " " << st.physics << endl;
}
out.close();
}
// 根据学号查找学生
Student* findById(string id) {
for (auto& st : students) {
if (st.id == id) {
return &st;
}
}
return nullptr;
}
public:
// 构造函数
StudentManager() {
readFromFile();
}
// 添加学生
void addStudent() {
string name, id, cls;
char gender;
int chinese, math, english, physics;
cout << "请输入学生姓名:";
cin >> name;
cout << "请输入学生性别(男/女):";
cin >> gender;
cout << "请输入学生学号:";
cin >> id;
cout << "请输入学生班级:";
cin >> cls;
cout << "请输入学生语文成绩:";
cin >> chinese;
cout << "请输入学生数学成绩:";
cin >> math;
cout << "请输入学生英语成绩:";
cin >> english;
cout << "请输入学生物理成绩:";
cin >> physics;
students.push_back(Student(name, gender, id, cls, chinese, math, english, physics));
cout << "学生信息添加成功!" << endl;
writeToFile();
}
// 修改学生信息
void modifyStudent() {
string id;
cout << "请输入要修改的学生学号:";
cin >> id;
Student* st = findById(id);
if (st == nullptr) {
cout << "未找到对应的学生信息!" << endl;
} else {
cout << "请输入新的学生姓名:";
cin >> st->name;
cout << "请输入新的学生性别(男/女):";
cin >> st->gender;
cout << "请输入新的学生班级:";
cin >> st->cls;
cout << "请输入新的学生语文成绩:";
cin >> st->chinese;
cout << "请输入新的学生数学成绩:";
cin >> st->math;
cout << "请输入新的学生英语成绩:";
cin >> st->english;
cout << "请输入新的学生物理成绩:";
cin >> st->physics;
st->total_score = st->chinese + st->math + st->english + st->physics;
cout << "学生信息修改成功!" << endl;
writeToFile();
}
}
// 删除学生
void deleteStudent() {
string id;
cout << "请输入要删除的学生学号:";
cin >> id;
auto it = students.begin();
while (it != students.end()) {
if (it->id == id) {
it = students.erase(it);
cout << "学生信息删除成功!" << endl;
writeToFile();
return;
} else {
++it;
}
}
cout << "未找到对应的学生信息!" << endl;
}
// 按照每个科目成绩排序
void sortBySubject() {
int choice;
cout << "请选择排序方式(1.语文 2.数学 3.英语 4.物理):";
cin >> choice;
switch (choice) {
case 1:
sort(students.begin(), students.end(), [](const Student& a, const Student& b) {
return a.chinese > b.chinese;
});
break;
case 2:
sort(students.begin(), students.end(), [](const Student& a, const Student& b) {
return a.math > b.math;
});
break;
case 3:
sort(students.begin(), students.end(), [](const Student& a, const Student& b) {
return a.english > b.english;
});
break;
case 4:
sort(students.begin(), students.end(), [](const Student& a, const Student& b) {
return a.physics > b.physics;
});
break;
default:
cout << "无效的选择!" << endl;
return;
}
cout << "按照科目成绩排序成功!" << endl;
}
// 按照总成绩排序
void sortByTotalScore() {
sort(students.begin(), students.end());
cout << "按照总成绩排序成功!" << endl;
}
// 统计平均分
void calculateAverageScore() {
int choice;
cout << "请选择统计方式(1.班级 2.科目):";
cin >> choice;
if (choice == 1) {
string cls;
cout << "请输入要统计的班级:";
cin >> cls;
int sum_chinese = 0, sum_math = 0, sum_english = 0, sum_physics = 0;
int count = 0;
for (auto& st : students) {
if (st.cls == cls) {
sum_chinese += st.chinese;
sum_math += st.math;
sum_english += st.english;
sum_physics += st.physics;
count++;
}
}
if (count > 0) {
cout << "班级:" << cls << endl;
cout << "语文平均分:" << sum_chinese / count << endl;
cout << "数学平均分:" << sum_math / count << endl;
cout << "英语平均分:" << sum_english / count << endl;
cout << "物理平均分:" << sum_physics / count << endl;
} else {
cout << "未找到对应的班级信息!" << endl;
}
} else if (choice == 2) {
int sum_chinese = 0, sum_math = 0, sum_english = 0, sum_physics = 0;
int count = students.size();
for (auto& st : students) {
sum_chinese += st.chinese;
sum_math += st.math;
sum_english += st.english;
sum_physics += st.physics;
}
cout << "科目平均分:" << endl;
cout << "语文:" << sum_chinese / count << endl;
cout << "数学:" << sum_math / count << endl;
cout << "英语:" << sum_english / count << endl;
cout << "物理:" << sum_physics / count << endl;
} else {
cout << "无效的选择!" << endl;
return;
}
}
// 根据学号查询学生信息
void queryById() {
string id;
cout << "请输入要查询的学生学号:";
cin >> id;
Student* st = findById(id);
if (st == nullptr) {
cout << "未找到对应的学生信息!" << endl;
} else {
cout << setw(10) << "姓名" << setw(5) << "性别" << setw(15) << "学号" << setw(10) << "班级";
cout << setw(5) << "语文" << setw(5) << "数学" << setw(5) << "英语" << setw(5) << "物理";
cout << setw(5) << "总分" << endl;
st->display();
}
}
// 根据姓名和班级查询学生信息
void queryByNameAndCls() {
string name, cls;
cout << "请输入要查询的学生姓名:";
cin >> name;
cout << "请输入要查询的学生班级:";
cin >> cls;
bool found = false;
cout << setw(10) << "姓名" << setw(5) << "性别" << setw(15) << "学号" << setw(10) << "班级";
cout << setw(5) << "语文" << setw(5) << "数学" << setw(5) << "英语" << setw(5) << "物理";
cout << setw(5) << "总分" << endl;
for (auto& st : students) {
if (st.name == name && st.cls == cls) {
st.display();
found = true;
}
}
if (!found) {
cout << "未找到对应的学生信息!" << endl;
}
}
// 显示菜单
void showMenu() {
cout << "======================================" << endl;
cout << "欢迎使用学生成绩管理系统!" << endl;
cout << "1.添加学生信息" << endl;
cout << "2.修改学生信息" << endl;
cout << "3.删除学生信息" << endl;
cout << "4.按照每个科目成绩排序" << endl;
cout << "5.按照总成绩排序" << endl;
cout << "6.统计平均分" << endl;
cout << "7.根据学号查询学生信息" << endl;
cout << "8.根据姓名和班级查询学生信息" << endl;
cout << "0.退出程序" << endl;
cout << "======================================" << endl;
}
// 运行程序
void run() {
int choice;
while (true) {
showMenu();
cout << "请输入要执行的操作序号:";
cin >> choice;
switch (choice) {
case 1:
addStudent();
break;
case 2:
modifyStudent();
break;
case 3:
deleteStudent();
break;
case 4:
sortBySubject();
break;
case 5:
sortByTotalScore();
break;
case 6:
calculateAverageScore();
break;
case 7:
queryById();
break;
case 8:
queryByNameAndCls();
break;
case 0:
cout << "感谢使用本系统,再见!" << endl;
return;
default:
cout << "无效的选择,请重新输入!" << endl;
break;
}
}
}
};
int main() {
StudentManager manager;
manager.run();
return 0;
}
```
程序中使用了文件存储学生信息,数据会被保存在名为“students.txt”的文件中。每次进行学生信息的添加、修改、删除等操作后,文件都会被更新。当程序启动时,会从文件中读取学生信息并存储到内存中,以便进行后续的查询和统计。
不使用SQL,必要时运用清屏等system指令,用c++实现以下主要功能: (1) 学生管理:对学生基本信息的增加、修改和删除 (2) 学生查询:对学生基本信息和成绩的查询 (3) 学生选课:用于学生选择课程学习 (4) 学生成绩:对学生各科成绩的添加、修改和删除等管理 (5) 打印:用来打印学生的基本信息和成绩 参考数据表: 学生(学号,姓名,性别,年级,出生年月,系号) 成绩(学号,成绩,课程号) 课程(课程号,课程名,学分,上课时间,选课人数)
这是一个比较复杂的项目,需要使用多个类和数据结构来实现。以下是一个简单的示例代码,供参考。
```cpp
#include <iostream>
#include <vector>
#include <cstdlib> // 用于清屏操作
using namespace std;
// 定义学生类
class Student {
public:
string id; // 学号
string name; // 姓名
string gender; // 性别
int grade; // 年级
string birthday; // 出生年月
string departmentId; // 系号
// 构造函数
Student(string id, string name, string gender, int grade, string birthday, string departmentId) {
this->id = id;
this->name = name;
this->gender = gender;
this->grade = grade;
this->birthday = birthday;
this->departmentId = departmentId;
}
// 输出学生信息
void printInfo() {
cout << "学号:" << id << endl;
cout << "姓名:" << name << endl;
cout << "性别:" << gender << endl;
cout << "年级:" << grade << endl;
cout << "出生年月:" << birthday << endl;
cout << "系号:" << departmentId << endl;
}
};
// 定义成绩类
class Score {
public:
string studentId; // 学号
double score; // 成绩
string courseId; // 课程号
// 构造函数
Score(string studentId, double score, string courseId) {
this->studentId = studentId;
this->score = score;
this->courseId = courseId;
}
// 输出成绩信息
void printInfo() {
cout << "学号:" << studentId << endl;
cout << "成绩:" << score << endl;
cout << "课程号:" << courseId << endl;
}
};
// 定义课程类
class Course {
public:
string id; // 课程号
string name; // 课程名
int credit; // 学分
string time; // 上课时间
int numStudents; // 选课人数
// 构造函数
Course(string id, string name, int credit, string time) {
this->id = id;
this->name = name;
this->credit = credit;
this->time = time;
this->numStudents = 0;
}
// 输出课程信息
void printInfo() {
cout << "课程号:" << id << endl;
cout << "课程名:" << name << endl;
cout << "学分:" << credit << endl;
cout << "上课时间:" << time << endl;
cout << "选课人数:" << numStudents << endl;
}
};
// 定义学生管理类
class StudentManager {
private:
vector<Student> students; // 存储学生信息的容器
vector<Score> scores; // 存储成绩信息的容器
public:
// 添加学生
void addStudent(string id, string name, string gender, int grade, string birthday, string departmentId) {
Student student(id, name, gender, grade, birthday, departmentId);
students.push_back(student);
}
// 修改学生信息
void modifyStudent(string id) {
for (int i = 0; i < students.size(); i++) {
if (students[i].id == id) {
cout << "请输入修改后的信息:" << endl;
cout << "学号:";
cin >> students[i].id;
cout << "姓名:";
cin >> students[i].name;
cout << "性别:";
cin >> students[i].gender;
cout << "年级:";
cin >> students[i].grade;
cout << "出生年月:";
cin >> students[i].birthday;
cout << "系号:";
cin >> students[i].departmentId;
cout << "修改成功!" << endl;
return;
}
}
cout << "未找到该学生!" << endl;
}
// 删除学生
void deleteStudent(string id) {
for (int i = 0; i < students.size(); i++) {
if (students[i].id == id) {
students.erase(students.begin() + i);
cout << "删除成功!" << endl;
return;
}
}
cout << "未找到该学生!" << endl;
}
// 查询学生信息
void queryStudent(string id) {
for (int i = 0; i < students.size(); i++) {
if (students[i].id == id) {
students[i].printInfo();
return;
}
}
cout << "未找到该学生!" << endl;
}
// 添加成绩
void addScore(string studentId, double score, string courseId) {
Score scoreObj(studentId, score, courseId);
scores.push_back(scoreObj);
}
// 修改成绩
void modifyScore(string studentId, string courseId) {
for (int i = 0; i < scores.size(); i++) {
if (scores[i].studentId == studentId && scores[i].courseId == courseId) {
cout << "请输入修改后的信息:" << endl;
cout << "成绩:";
cin >> scores[i].score;
cout << "修改成功!" << endl;
return;
}
}
cout << "未找到该学生的该门课程成绩!" << endl;
}
// 删除成绩
void deleteScore(string studentId, string courseId) {
for (int i = 0; i < scores.size(); i++) {
if (scores[i].studentId == studentId && scores[i].courseId == courseId) {
scores.erase(scores.begin() + i);
cout << "删除成功!" << endl;
return;
}
}
cout << "未找到该学生的该门课程成绩!" << endl;
}
// 查询学生所有成绩
void queryScore(string studentId) {
bool found = false;
for (int i = 0; i < scores.size(); i++) {
if (scores[i].studentId == studentId) {
found = true;
for (int j = 0; j < students.size(); j++) {
if (students[j].id == studentId) {
cout << "学生姓名:" << students[j].name << endl;
break;
}
}
scores[i].printInfo();
cout << endl;
}
}
if (!found) {
cout << "未找到该学生的成绩!" << endl;
}
}
// 选课
void selectCourse(string studentId, string courseId) {
bool found = false;
for (int i = 0; i < scores.size(); i++) {
if (scores[i].studentId == studentId && scores[i].courseId == courseId) {
found = true;
cout << "你已经选过该门课程!" << endl;
break;
}
}
if (!found) {
for (int i = 0; i < courses.size(); i++) {
if (courses[i].id == courseId) {
if (courses[i].numStudents >= 100) {
cout << "该门课程已满员,无法选课!" << endl;
break;
}
courses[i].numStudents++;
addScore(studentId, 0, courseId);
cout << "选课成功!" << endl;
break;
}
}
}
}
// 输出所有学生信息
void printAllStudents() {
for (int i = 0; i < students.size(); i++) {
students[i].printInfo();
cout << endl;
}
}
// 输出所有课程信息
void printAllCourses() {
for (int i = 0; i < courses.size(); i++) {
courses[i].printInfo();
cout << endl;
}
}
private:
vector<Course> courses = { // 存储课程信息的容器
Course("001", "语文", 3, "周一上午"),
Course("002", "数学", 4, "周二上午"),
Course("003", "英语", 2, "周三下午"),
Course("004", "物理", 3, "周四上午"),
Course("005", "化学", 3, "周五下午")
};
};
// 主函数
int main() {
StudentManager manager;
while (true) {
cout << "请选择操作:" << endl;
cout << "1. 添加学生" << endl;
cout << "2. 修改学生信息" << endl;
cout << "3. 删除学生" << endl;
cout << "4. 查询学生信息" << endl;
cout << "5. 添加成绩" << endl;
cout << "6. 修改成绩" << endl;
cout << "7. 删除成绩" << endl;
cout << "8. 查询学生所有成绩" << endl;
cout << "9. 选课" << endl;
cout << "10. 输出所有学生信息" << endl;
cout << "11. 输出所有课程信息" << endl;
cout << "0. 退出程序" << endl;
int choice;
cin >> choice;
switch (choice) {
case 1: { // 添加学生
cout << "请输入学生信息:" << endl;
string id, name, gender, birthday, departmentId;
int grade;
cout << "学号:";
cin >> id;
cout << "姓名:";
cin >> name;
cout << "性别:";
cin >> gender;
cout << "年级:";
cin >> grade;
cout << "出生年月:";
cin >> birthday;
cout << "系号:";
cin >> departmentId;
manager.addStudent(id, name, gender, grade, birthday, departmentId);
cout << "添加成功!" << endl;
break;
}
case 2: { // 修改学生信息
cout << "请输入要修改的学生学号:";
string id;
cin >> id;
manager.modifyStudent(id);
break;
}
case 3: { // 删除学生
cout << "请输入要删除的学生学号:";
string id;
cin >> id;
manager.deleteStudent(id);
break;
}
case 4: { // 查询学生信息
cout << "请输入要查询的学生学号:";
string id;
cin >> id;
manager.queryStudent(id);
break;
}
case 5: { // 添加成绩
cout << "请输入成绩信息:" << endl;
string studentId, courseId;
double score;
cout << "学号:";
cin >> studentId;
cout << "课程号:";
cin >> courseId;
cout << "成绩:";
cin >> score;
manager.addScore(studentId, score, courseId);
cout << "添加成功!" << endl;
break;
}
case 6: { // 修改成绩
cout << "请输入要修改的学生学号和课程号:";
string studentId, courseId;
cin >> studentId >> courseId;
manager.modifyScore(studentId, courseId);
break;
}
case 7: { // 删除成绩
cout << "请输入要删除的学生学号和课程号:";
string studentId, courseId;
cin >> studentId >> courseId;
manager.deleteScore(studentId, courseId);
break;
}
case 8: { // 查询学生所有成绩
cout << "请输入要查询的学生学号:";
string id;
cin >> id;
manager.queryScore(id);
break;
}
case 9: { // 选课
cout << "请输入学生学号和课程号:";
string studentId, courseId;
cin >> studentId >> courseId;
manager.selectCourse(studentId, courseId);
break;
}
case 10: { // 输出所有学生信息
manager.printAllStudents();
break;
}
case 11: { // 输出所有课程信息
manager.printAllCourses();
break;
}
case 0: { // 退出程序
return 0;
}
default: { // 输入错误
cout << "输入错误,请重新输入!" << endl;
break;
}
}
system("pause"); // 暂停程序,等待用户按下任意键继续
system("cls"); // 清屏
}
return 0;
}
```
相关推荐
![pdf](https://img-home.csdnimg.cn/images/20210720083512.png)
![pdf](https://img-home.csdnimg.cn/images/20210720083512.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![pdf](https://img-home.csdnimg.cn/images/20210720083512.png)