3.11 封装集合

【1】封装集合

范例：

#include <QString>
#define MAX_STUDENT_COUNT 20

class Student
{
public:
    Student(int nId, QString name = QString(), QString department = QString("jisuanji"))
        : m_nID(nId)
        , m_name(name)
        , m_department(department)
    {}

    int getId() const
    {
        return m_nID;
    }
    void setId(int nId)
    {
        m_nID = nId;
    }
    QString getName() const
    {
        return m_name;
    }
    void setName(QString name)
    {
        m_name = name;
    }
    QString getDepartment() const
    {
        return m_department;
    }
    void setDepartment(QString department)
    {
        m_department = department;
    }

    bool operator ==(const Student& student) const
    {
        return (student.getId() == m_nID &&
                student.getName() == m_name &&
                student.getDepartment() == m_department);
    }

private:
    int m_nID;
    QString m_name;
    QString m_department;
};

class School
{
public:
    School()
    {
        for (int i = 1; i < MAX_STUDENT_COUNT + 1; ++i)
        {
            m_students.append(*(new Student(i)));
        }
    }

    // 获取到的仅仅只是一个副本
    const QList<Student> getStudents()
    {
        return m_students;
    }

    void addStudent(Student student)
    {
        m_students.append(student);
    }

    void removeStudent(int nId)
    {
        QList<Student>::const_iterator cIter = m_students.cbegin();
        while (cIter != m_students.cend())
        {
            if ((*cIter).getId() == nId)
            {
                m_students.removeOne(*cIter);
                return;
            }
            ++cIter;
        }
    }

private:
    QList<Student> m_students; // 集合
};

/*
 * 有个函数返回一个集合。让这个函数返回该集合的一个只读副本，并在这个类中提供添加/移除集合元素的函数。
 */

void main()
{
    School school;
    QList<Student> studentList = school.getStudents();
    Student student(22, "liu", "math");
    school.addStudent(student);
    school.removeStudent(12);
}

【2】总结

有个函数返回一个集合。让这个函数返回该集合的一个只读副本，并在这个类中提供添加/移除集合元素的函数。

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