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// ==================================================
// - File______: ce241-fall08-hw8-all.cpp ___________
// - Author____: Ahmet Ardal ________________________
// - Contact___: ardalahmet@hotmail.com _____________
// - Date______: ??/12/2008 _________________________
// __________________________________________________
// - Copyright (c) 2008, Some Rights Reserved _______
// ==================================================

#include <iostream>

using namespace std;

// struct declaration
struct GradeNode
{
    int id;
    int grade;

    GradeNode *pNext;
};

// function declarations
GradeNode *newGradeNode(int id, int grade);
void       appendGrade(GradeNode *pHead, int id, int grade);
GradeNode *findGradeById(const GradeNode *pHead, int id);
void       printGradeList(const GradeNode *pHead);
GradeNode *deleteFirstGrade(GradeNode *pHead);
void       destroyGradeList(GradeNode *pHead);

int main()
{
    // pointer to the first item in the list
    GradeNode *pHead;

    // create the first node of the list
    pHead = new GradeNode;
    pHead->id = 77;
    pHead->grade = 70;
    pHead->pNext = NULL;

    // use appendGrade() function to add items to the list
    for (int i = 0; i < 5; ++i)
    {
        appendGrade(pHead, i, (i * i));
    }

    // use findGradeById() function to find a specific grade in the list
    GradeNode *pNode = findGradeById(pHead, 3);
    if (pNode == NULL)
    {
        cout << "cannot find grade with id: " << 3 << endl;
    }
    else
    {
        cout << "grade found: " << pNode->grade << endl;
    }

    // use findGradeById() function to find a specific grade in the list
    pNode = findGradeById(pHead, 300);
    if (pNode == NULL)
    {
        cout << "cannot find grade with id: " << 300 << endl;
    }
    else
    {
        cout << "grade found: " << pNode->grade << endl;
    }

    // use printGradeList() function to print grades in the list
    cout << endl << "printing the list: " << endl;
    printGradeList(pHead);

    // use deleteFirstGrade() function to delete top two items from the list,
    // and print the list to see whether deletions were successful
    pHead = deleteFirstGrade(pHead);
    pHead = deleteFirstGrade(pHead);
    cout << endl << "printing the list after deletions: " << endl;
    printGradeList(pHead);

    // destroy the list and free all dynamically allocated memory
    destroyGradeList(pHead);

    return 0;
}

// function definitions
GradeNode *newGradeNode(int id, int grade)
{
    GradeNode *pGradeNode = new GradeNode;

    pGradeNode->id    = id;
    pGradeNode->grade = grade;
    pGradeNode->pNext = NULL;

    return pGradeNode;
}

void appendGrade(GradeNode *pHead, int id, int grade)
{
    if (pHead == NULL)
    {
        return;
    }

    GradeNode *pNewGradeNode = newGradeNode(id, grade);
    GradeNode *pNode;

    for (pNode = pHead; ; pNode = pNode->pNext)
    {
        if (pNode->pNext == NULL)
        {
            break;
        }
    }

    pNode->pNext = pNewGradeNode;
}

GradeNode *findGradeById(const GradeNode *pHead, int id)
{
    for (GradeNode *pNode = (GradeNode *) pHead; pNode != NULL; pNode = pNode->pNext)
    {
        if (pNode->id == id)
        {
            return pNode;
        }
    }

    return NULL;
}

void printGradeList(const GradeNode *pHead)
{
    for (const GradeNode *pNode = pHead; pNode != NULL; pNode = pNode->pNext)
    {
        cout << "id: " << pNode->id << ", grade: " << pNode->grade << endl;
    }
}

GradeNode *deleteFirstGrade(GradeNode *pHead)
{
    GradeNode *pNewHead = pHead->pNext;

    delete pHead;
    return pNewHead;
}

void destroyGradeList(GradeNode *pHead)
{
    // destroy the list and free all dynamically allocated memory
    for (GradeNode *pNode = pHead; pNode != NULL; )
    {
        GradeNode *pTmpNode = pNode->pNext;

        delete pNode;
        pNode = pTmpNode;
    }
}