C++链表实现学生成绩管理（增删改查）

简介：并未封装成类，功能也仅实现了增删改查。数据为txt，格式：学号（long） 姓名（string） 总分（int）

学生信息结构体

struct Student {
    long m_id;
    string m_name;
    int m_score;
};

节点结构体

struct Node {
    Student data;
    Node* next;

    Node() { next = nullptr; }
};

读取data.txt获取数据

Node* ReadInformation(Node* root) {
    if (!root) root = new Node();//防止输入一个未初始化的指针

    Node* p = root;
    Node* q = nullptr;//去掉最后的空指针

    ifstream in("data.txt");

    long id;
    string name;
    int score;
    while (!in.eof()) {
        in >> id >> name >> score;
        p->data.Set(id, name, score);
        p->next = new Node();
        q = p;
        p = p->next;
    }
    q->next = nullptr;
    delete p;
    p = nullptr;
    in.close();
    return root;//返回首指针
}

输出全部信息

void Print(Node* root) {
    if (!root) return;
    Node* p = root;
    cout << setw(6) << "ID" << setw(8) << "Name" << setw(6) << "Score\n";
    while (p) {
        cout << setw(6) << p->data.m_id
            << setw(8) << p->data.m_name
            << setw(6) << p->data.m_score
            << endl;
        p = p->next;
    }
    cout << endl;
}

四个基本功能：增删改查

增Add：首端插入

Node* Add(Node* root, const Student& stu) {
    Node* p = new Node();
    p->data = stu;
    p->next = root;
    return p;
}

删Delete：

//遍历 删除stu对应节点，然后返回头指针
Node* Delete(Node* root, const Student& stu) {
    if (!root) {
        cout << "No information to delete.\n";
        return root;
    }
    Node* q = root;
    Node* p = q->next;
    //检查第一个
    if (q->data == stu) {
        root = root->next;
        delete q;
        q = nullptr;
        return root;
    }
    while (p) {
        if (p->data == stu) {
            q->next = p->next;
            delete p;
            p = nullptr;
            return root;
        }
    }
    cout << "No such information to delete.\n";
    return root;
}

改Modify：

//找到index:从0开始(并非id） 对应的节点，输入修改后的信息，修改，然后返回头指针
void Modify(Node* root, const int& index) {
    if (!root) {
        cout << "There is no information to modify.\n";
        return;
    }
    Node* p = root;
    int i(0);
    while (p) {
        if (i == index) {
            cout<<"Information;"<< p->data.m_id
                << setw(8) << p->data.m_name
                << setw(6) << p->data.m_score
                << endl;
            long id;
            string name;
            int score;
            char c;
            cout << "New:";
            cin >> id >> name >> score;
            cout << "Are you sure to modify the information? \nEnter:";
            cin >> c;
            if (c == 'Y' || c == 'y') {
                p->data.Set(id, name, score);
                return;
            }
            else return;
        }
        p = p->next;
        ++i;
    }
    cout << "The index:" << index << " is too big.\n"
        << "There are " << i+1 << " students.\n";
}

查Find：分为id、name、score range三种查找

Node* Find(Node* root,const int& cho) { if (!root) { cout << "The linklist is empty.\n"; return nullptr; } long id; string name; int sco1, sco2; Node* p = nullptr; switch (cho) { case 1: cout << "Please input Id:"; cin >> id; p=FindById(root,id); break; case 2: cout << "Please input Name:"; cin >> name; p=FindByName(root,name); break;

case 3: cout << "Please input Score's range:"; cin >> sco1 >> sco2; p = FindByScore(root, sco1, sco2);

                break; default: break; }

         if (!p) cout << "Not found.\n";return p; }

Node* FindById(Node* root,const long& id) { Node* p = root; while (p) { if (p->data.m_id == id) { cout << setw(6) << p->data.m_id << setw(8) << p->data.m_name << setw(6) << p->data.m_score << endl; return p; } p = p->next; } return nullptr; } Node* FindByName(Node* root,const string& name) { Node* p = root; Node* res=nullptr; int count(0); while (p) { if (p->data.m_name == name) { cout << setw(6) << p->data.m_id << setw(8) << p->data.m_name << setw(6) << p->data.m_score << endl; ++count; if (count == 1) res = p; } p = p->next; } return res; } Node* FindByScore(Node* root,const int& sco1,const int& sco2) { if (sco1 > sco2) { cout << "Error input.\n"; return nullptr; } Node* p = root; Node* res = nullptr;

        int count(0); while (p) { if (p->data.m_score >= sco1 && p->data.m_score <= sco2) { cout << setw(6) << p->data.m_id << setw(8) << p->data.m_name << setw(6) << p->data.m_score << endl; ++count; if (count == 1) res = p; } p = p->next; } return res; }

测试：main.cpp

bool IsUnique(Node* root, const long& id) {          if (!root) return true;          Node* p = root;          while (p) {               if (p->data.m_id == id) {                return false;           }           p = p->next;          }          return true; }

Node* link=nullptr; int main() { link = ReadInformation(link); { cout << "0.Exit\n"; cout << "1.Add\n"; cout << "2.Delete\n"; cout << "3.Modify\n"; cout << "4.Find\n"; cout << "5.Print\n\n\n"; } int cho; int cho2; do{ cout << "Enter: "; cin >> cho;

Student s; int index;

switch (cho) { case 0:break; case 1: cout << "Information:"; cin >> s.m_id >> s.m_name >> s.m_score; //check id avoid the same id if (!IsUnique(link, s.m_id)) { cout << "Id has existed.\n"; break; } link = Add(link, s); break; case 2: cout << "Information:"; cin >> s.m_id >> s.m_name >> s.m_score; link = Delete(link, s); break; case 3: cout << "Index:"; cin >> index; Modify(link, index); break; case 4: cout << "1.Find by Id\n" << "2.Find by Name\n" << "3.Find by Score's range\n" << "Enter:"; cin >> cho2; Find(link, cho2); break; case 5: Print(link); break; } } while (cho); system("pause"); return 0; }

运行截图：