cis22c/04-dl-lists/StudentList.cpp

140 lines
4.1 KiB
C++

// Sorted Circular Doubly-Linked List with Sentinel Node
// Implementation file for the Student List class
// Written by: Iurii Tatishchev
// Reviewed & Modified by: Iurii Tatishchev
// IDE: CLion
#include <iostream> // For cout and NULL
#include "StudentList.h"
using namespace std;
// **************************************************
// Constructor
// This function allocates and initializes a sentinel node
// A sentinel (or dummy) node is an extra node added before the first data record.
// This convention simplifies and accelerates some list-manipulation algorithms,
// by making sure that all links can be safely dereferenced and that every list
// (even one that contains no data elements) always has a "first" node.
// **************************************************
StudentList::StudentList() {
head = new ListNode; // head points to the sentinel node
head->stu.gpa = -1;
head->stu.name = "";
head->forw = head;
head->back = head;
count = 0;
}
// **************************************************
// display list forwards: shows the value
// stored in each node of the linked list
// pointed to by head. from A to Z
// **************************************************
void StudentList::displayListForw() const {
ListNode *pCur; // To move through the list
// Position pCur: skip the head of the list.
pCur = head->forw;
// While pCur points to a node, traverse the list.
while (pCur != head) {
// Display the value in this node.
cout << pCur->stu.gpa << " " << pCur->stu.name << endl;
// Move to the next node.
pCur = pCur->forw;
}
cout << endl;
}
// **************************************************
// display list backwards: shows the value
// stored in each node of the linked list
// pointed to by head, from Z to A
// **************************************************
void StudentList::displayListBack() const {
ListNode *pCur; // To move through the list
// Position pCur: skip the head of the list.
pCur = head->back;
// While pCur points to a node, traverse the list.
while (pCur != head) {
// Display the value in this node.
cout << pCur->stu.gpa << " " << pCur->stu.name << endl;
// Move to the next node.
pCur = pCur->back;
}
cout << endl;
}
// **************************************************
// The insertNode function inserts a node with
// stu copied to its value member.
// **************************************************
void StudentList::insertNode(Student dataIn) {
ListNode *newNode; // A new node
ListNode *pCur; // To traverse the list
// Allocate a new node and store num there.
newNode = new ListNode;
newNode->stu = dataIn;
// Initialize pointers
pCur = head->forw;
// Find location: skip all nodes whose name is less than dataIn's name
while (pCur != head && pCur->stu.name < dataIn.name) {
pCur = pCur->forw;
}
// Insert the new node between pPre and pCur
ListNode *pPre = pCur->back; // The previous node
pPre->forw = newNode;
newNode->forw = pCur;
pCur->back = newNode;
newNode->back = pPre;
// Update the counter
count++;
}
// **************************************************
// The deleteNode function deletes a node with
// the same key as its paramenter, if found
// **************************************************
bool StudentList::deleteNode(string target) {
ListNode *pCur; // To traverse the list
bool success = false;
pCur = head->forw;
while (pCur != head && pCur->stu.name < target) {
pCur = pCur->forw;
}
if (pCur != head && pCur->stu.name == target) {
ListNode *pPrev = pCur->back;
ListNode *pNext = pCur->forw;
pPrev->forw = pNext;
pNext->back = pPrev;
delete pCur;
success = true;
count--;
}
return success;
}
// **************************************************
// Destructor *
// This function deletes every node in the list. *
// **************************************************
StudentList::~StudentList() {
}