링 버퍼 구현 과제 1

Ring Buffer.c

#include <stdio.h>
#define MAX_SIZE 5

// global variables
int queue[MAX_SIZE];
int front = 0;
int rear = 0;

// check if queue is full
int queue_full()
{
    // return 0 only if the above condition is false
    return (front == 1 && rear == MAX_SIZE) || front == rear + 1;
}

// check if queue is empty
int queue_empty()
{
    // return 0 only if the above condition is false
    return front == 0;
}

// add an element to the queue
void enqueue(int x)
{
    // check if queue is full
    if (queue_full())
    {
        printf("Queue is overflow, ");
        return;
    }

    if (rear == MAX_SIZE)
        rear = 1;
    else if (front == 0 && rear == 0)
    {
        front = 1;
        rear++;
    }
    else
        rear++;

    queue[rear] = x;
}

// remove an element from the queue
int dequeue()
{
    // check if queue is empty
    if (queue_empty())
    {
        printf("Queue is underflow, ");
        return -1;
    }

    int temp = queue[front];

    if (front == MAX_SIZE)
        front = 1;
    else if (front == rear)
    {
        front = 0;
        rear = 0;
    }
    else
        front++;

    return temp;
}

// helper function: print the current queue
void print_queue()
{
    int front_pos = front, rear_pos = rear;
    printf("queue =");

    // if queue is empty
    if (!queue_empty())
    {
        // normal case of queue
        if (front_pos <= rear_pos) {
            while (front_pos <= rear_pos)
            {
                printf(" %d", queue[front_pos]);
                front_pos++;
            }
        }
        else
        {
            // special case of queue (front_pos > rear_pos)
            while (front_pos <= MAX_SIZE)
            {
                printf(" %d", queue[front_pos]);
                front_pos++;
            }

            front_pos = 1;
            while (front_pos <= rear_pos)
            {
                printf(" %d", queue[front_pos]);
                front_pos++;
            }
        }
    }

    // print front and rear
    printf(" (rear=%d, front=%d)\n", rear, front);
}

int main()
{
    int insert_test[] = { 10, 50, 20, 70 };

    for (int i = 0; i < 4; i++)
    {
        printf("enqueue(%d), ", insert_test[i]);
        enqueue(insert_test[i]);
        print_queue();
    }

    printf("dequeue() = %d, ", dequeue());
    print_queue();

    int insert_test2[] = { 100, 40, 140, 70 };

    for (int i = 0; i < 3; i++)
    {
        printf("enqueue(%d), ", insert_test2[i]);
        enqueue(insert_test2[i]);
        print_queue();
    }

    for (int i = 0; i < 3; i++)
    {
        printf("dequeue() = %d, ", dequeue());
        print_queue();
    }
}