C++ Course::remove_student方法代码示例

void 
remove_student()
{
	int indexValue;  // Index location of student to be removed.
	bool test;		 // Test variable for removal of students from course lists.
	
	Student *tempStudent;  // Points to any student object
	Course *tempCourse;	   // Points to any course object
	LinkedList &sList = master_student_list();  // reference to master student list.
	LinkedList &cList = master_course_list();   // reference to master course list. 

	if (sList.size() <= 0)  // Attempts to acces an empty list may cause crashes.
	{
		cerr << "\n*** The List is Empty ***" << endl;
		return;
	}

	// Ask the user for a student number and search for that student.
	indexValue = find_student(sList);

	if (indexValue == -1)  // ie. if the student was not found!
	{
		cerr << "\n*** No Student of that Number in the List ***" << endl;
		return;
	}

	// If the student WAS found then do the following.
	
	// Remove student from the list and get a pointer to the student object.
	tempStudent = (Student*)sList.remove(indexValue);
	
	// Remove this student from all course lists.
	for (int i = 0; i < cList.size(); i++)
	{
		tempCourse = (Course*)cList[i];

		// Remove the Student from the Course's List of Students
		// Note that remove_student checks if the student is in a particular
		// course before doing anything.
		test = tempCourse->remove_student(tempStudent);
	}

	// Now that the course lists have been cleaned up we can delete the student.
	delete tempStudent;
		
	//  NO NEED to fill in the empty space created by shifting values "up".
	//  Since this is a linked list the objects are not placed sequentially
	//  in memory.  The remove function just rearranges the links so that the 
	//  object removed is no longer part of the link.
}

void 
remove_course(LinkedList &sList)
{
	int sIndex;			  // Index location of target student.
	int cIndex;			  // Index location of target course.
	Student *tempStudent; // Pointer to target student object.
	Course *tempCourse;	  // Pointer to target course object.
	bool test;			  // Bool variable, for testing whether student was 
						  // successfully removed from a Course's List.
	
	// Get the student of interest from the user.
	sIndex = find_student(sList);
	
	// If the student was not found display error message and return.
	if (sIndex == -1)
	{
		cerr << "\n*** No Student of that Number in the List ***" << endl;
		return;
	}

	tempStudent = (Student*)sList[sIndex];

	// Get a local copy of the student's course list
	LinkedList &cList = tempStudent->get_course_list();

	// Check for course list is empty for this student, if so, return.
	if (cList.size() == 0)
	{
		cerr << "\n*** Student is not enrolled in any courses ***" << endl;
		return;
	}

	// Display this student's courses.
	tempStudent->print_courses();

	// Ask user which course to remove
	cout << "Which course would you like to remove (enter number) > ";
	cin >> cIndex;

	// Check that the user's entry is valid
	if (cIndex > cList.size() || cIndex <= 0)
	{
		cerr << "\n*** Not a Valid Course Entry ***" << endl;
		return;
	}

	tempCourse = (Course*)cList[cIndex-1];  // Must adjust index value.

	// Now that everything has been checked, actually remove the course.
	// Do not delete memory for that course because student does not OWN 
	// the course objects.
	tempStudent->remove_course(tempCourse);

	// Remove the Student from the Course's List of Students
	test = tempCourse->remove_student(tempStudent);

	// Error checking.
	if (test)
		cout << "\nEnrollment for this Course updated successfully" << endl;
	else
		cerr << "\n*** Update of Enrollment for this course failed ***" << endl;
}