C++(类模板的运用)

 

使用vector实现一个简单的本地注册登录系统 注册：将账号密码存入vector里面，注意防重复判断 登录：判断登录的账号密码是否正确 

#include <iostream>
#include <vector>
#include <fstream>
#include <sstream>
using namespace std;

struct usr {
    string pin;
    string psw;
};

vector<usr> readUsers(const string& filename) {
    vector<usr> users;
    ifstream infile(filename);
    string pin, psw;
    while (infile >> pin >> psw) {
        users.push_back({pin, psw});
    }
    infile.close();
    return users;
}

bool isDuplicate(const vector<usr>& users, const string& pin) {
    for (const auto& u : users) {
        if (u.pin == pin) {
            return true;
        }
    }
    return false;
}

bool loginValid(const vector<usr>& users, const string& pin, const string& psw) {
    for (const auto& u : users) {
        if (u.pin == pin && u.psw == psw) {
            return true;
        }
    }
    return false;
}

void writeUser(const string& filename, const usr& user) {
    ofstream outfile(filename, ios::app); // 追加写入
    outfile << user.pin << " " << user.psw << endl;
    outfile.close();
}

int main() {
    const string filename = "1.txt";

    while (true) {
        cout << "选择操作：" << endl;
        cout << "1. 注册" << endl;
        cout << "2. 登录" << endl;
        cout << "3. 退出" << endl;

        int choice;
        cin >> choice;

        if (choice == 1) {
            usr user;
            cout << "请输入账号和密码：" << endl;
            cin >> user.pin >> user.psw;

            vector<usr> users = readUsers(filename);
            if (isDuplicate(users, user.pin)) {
                cout << "账号已存在" << endl;
            } else {
                writeUser(filename, user);
                cout << "注册成功" << endl;
            }
        }
        else if (choice == 2) {
            string pin, psw;
            cout << "请输入账号和密码：" << endl;
            cin >> pin >> psw;

            vector<usr> users = readUsers(filename);
            if (loginValid(users, pin, psw)) {
                cout << "登录成功" << pin << endl;
            } else {
                cout << "登录失败" << endl;
            }
        }
        else if (choice == 3) {
            cout << "已退出" << endl;
            break;
        }
        else {
            cout << "请输入正确选项" << endl;
        }

        cout << endl;
    }

    return 0;
}