软件设计七

代码：#include <iostream> 

#include <string> 

#include <mutex> 

 

// StudentIdGenerator class 

class StudentIdGenerator { 

private: 

    static StudentIdGenerator* instance; 

    static std::mutex mtx; 

    std::string lastGeneratedId; 

    int counter; // 用于生成唯一的学号（示例中简单递增） 

 

    // Private constructor to prevent instantiation 

    StudentIdGenerator() : counter(0) { 

        lastGeneratedId = "000001"; // 假设第一个学号是000001 

    } 

 

public: 

    // Static method to return the unique instance 

    static StudentIdGenerator* getInstance() { 

        std::lock_guard<std::mutex> lock(mtx); 

        if (instance == nullptr) { 

            instance = new StudentIdGenerator(); 

        } 

        return instance; 

    } 

 

    // Method to generate the next unique student ID 

    std::string generateNextId() { 

        std::lock_guard<std::mutex> lock(mtx); 

        std::string newId = lastGeneratedId; 

        // 这里简单地通过递增数字来生成新的学号（实际应用中可能更复杂） 

        counter++; 

        std::ostringstream oss; 

        oss << std::setfill('0') << std::setw(6) << counter + 1; 

        lastGeneratedId = oss.str(); 

        return newId; 

    } 

}; 

 

// Static member initialization 

StudentIdGenerator* StudentIdGenerator::instance = nullptr; 

std::mutex StudentIdGenerator::mtx; 

 

// Student class 

class Student { 

private: 

    std::string studentId; 

 

public: 

    // Constructor that takes a StudentIdGenerator to get a unique ID 

    Student(StudentIdGenerator& idGenerator) { 

        studentId = idGenerator.generateNextId(); 

    } 

 

    // Method to get the student ID 

    std::string getStudentId() const { 

        return studentId; 

    } 

}; 

 

int main() { 

    // Get the unique instance of the StudentIdGenerator 

    StudentIdGenerator* idGenerator = StudentIdGenerator::getInstance(); 

 

    // Create students and print their IDs 

    Student student1(*idGenerator); 

    Student student2(*idGenerator); 

 

    std::cout << "Student 1 ID: " << student1.getStudentId() << std::endl; 

    std::cout << "Student 2 ID: " << student2.getStudentId() << std::endl; 

 

    return 0; 

}