example1.cpp
------------------------------------------------------

#include <iostream>
#define SIZE 10
int list[SIZE] = {12, 23, 34, 45, 56, 67, 78};
int total = 7;
void insertData(int data, int p);
void deleteData(int p);
void printList(const char *words);
using namespace std;

int main(){
    printList("Printing list");
    insertData(39, 3);
    printList("After inserting 39 at 3");
    deleteData(2);
    printList("After deleting item 2");
    return 0;
}
void printList(const char *words){
    cout << words << endl;
    if (total > 0)
    {
        for (int i = 0; i < total; i++)
            cout << list[i] << " ";
        cout << endl << endl;
    }
    else
        cout << "List is empty" << endl;
}
void insertData(int data, int p){
    if (total >= SIZE){
        cout << "List is full. Cannot insert data." << endl;
        return;
    }
    if (p < 0 || p > total){
        cout << "Invalid position. Cannot insert data." << endl;
        return;
    }
    for (int i = total; i > p; i--)
        list[i] = list[i - 1];

    list[p] = data;
    total++;
}
void deleteData(int p){
    if (total <= 0){
        cout << "List is empty. Cannot delete data." << endl;
        return;
    }
    if (p < 0 || p >= total){
        cout << "Invalid position. Cannot delete data." << endl;
        return;
    }
    for (int i = p; i < total - 1; i++)
        list[i] = list[i + 1];

    total--;
}

=============================================================
example2.cpp
#include <iostream>
#define SIZE 4

using namespace std;

int STACK[SIZE];
int TOP = -1;

void push(int data){
    if (TOP < SIZE - 1){
        TOP++;
        STACK[TOP] = data;
    }
    else
        cout << "Stack is full" << endl;
}

int pop(){
    int data;

    if (TOP > -1){
        data = STACK[TOP];
        TOP--;
        return data;
    }

    return -999;
}

void printstack(){
    int i;
    for (i = 0; i <= TOP; i++)
        cout << STACK[i] << ", ";
    cout << endl;
}

int main(){
    
    push(52);
    push(85);
    printstack();
    cout << "POP out: " << pop() << endl;
    cout << "POP out: " << pop() << endl;

    return 0;
}

==========================================================
example3.cpp
-----------------------------------------

#include <iostream>
using namespace std;

#define TOTALSIZE 6

int head = 0, tail = -1, q[TOTALSIZE];

void enqueue(int data){
    if (tail <= TOTALSIZE - 2)
    {
        tail++;
        q[tail] = data;
    }
    else
        cout << "queue is full" << endl;
}
int dequeue(){
    int data;
    if (head <= tail){
        data = q[head];
        head++;
        return data;
    }
    return -999;
}

void display(){
    int i;
    for (i = head; i <= tail; i++)
        cout << q[i] << ", ";
    cout << endl;
}

int main(void){
    int element, option;

    while (true){
        do{
            cout << "Queue Operations:" << endl;
            cout << "1. Enqueue" << endl;
            cout << "2. Dequeue" << endl;
            cout << "3. Display" << endl;
            cout << "> ";
            cin >> option;
            if (option == 1){
                cout << "Element = ";
                cin >> element;
            }
        } while (option != 1 && option != 2 && option != 3);

        if (option == 1)
            enqueue(element);
        else if (option == 2){
            element = dequeue();
            if (element != -999)
                cout << "Dequeue element=" << element << endl;
        }
        else{
            display();
        }
    }

    return 0;
}

======================================================

example4.cpp
------------------------------------------

#include <iostream>
#define size 6

using namespace std;

int head, tail, q[size];

void initialize(){
    head = 0;
    tail = -1;
}
bool empty(){
    if (head == 0 && tail == -1)
        return true;
    else
        return false;
}
bool full(){
    if ((tail + 1) % size == head && tail != -1)
        return true;
    else
        return false;
}

bool enqueue(int element){
    if (full()){
        cout << "Queue overflow" << endl;
        return false;
    }
    else{
        tail = (tail + 1) % size;
        q[tail] = element;
        return true;
    }
}

bool dequeue(int *element){
    if (empty()){
        cout << "Queue underflow" << endl;
        return false;
    }
    else{
        *element = q[head];
        if (head == tail)
            initialize();
        else{
            head = (head + 1) % size;
        }
        return true;
    }
}
void display(){
    int i = head;
    cout << "in display" << endl;
    if (!empty()){
        while (i != tail){
            cout << q[i] << ", ";
            i = (i + 1) % size;
        }
        cout << q[tail] << ", ";
    }
    cout << endl << endl;
}

int main(void){
    bool success;
    int element, option;

    initialize();

    while (true){
        do{
            cout << "Queue Operations:" << endl;
            cout << "1. Enqueue" << endl;
            cout << "2. Dequeue" << endl;
            cout << "3. Display" << endl;
            cout << "> ";
            cin >> option;
            if (option == 1){
                cout << "Element = ";
                cin >> element;
            }
        } while (option != 1 && option != 2 && option != 3);
        if (option == 1)
            success = enqueue(element);
        else if (option == 2){
            success = dequeue(&element);
            if (success)
                cout << "Dequeue element = " <<element << endl;
        }
        else{
            display();
        }
    }
    return 0;
}