queue-linkedlist.c

queue-linkedlist.c

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>


struct Node {
    int value;
    struct Node *next;
};

struct Node* newNode(int value){
    struct Node *node = (struct Node*)malloc(sizeof(struct Node));

    node->value = value;
    node->next = NULL;

    return node;
}


struct Queue {
    struct Node *head;
    struct Node *tail;
};


struct Queue* newQueue() {
    struct Queue *queue = (struct Queue*)malloc(sizeof(struct Queue));

    queue->head = NULL;
    queue->tail = NULL;

    return queue;
}

void enqueue(struct Queue *queue, int value){
    struct Node *node = newNode(value);

    if (queue->head == NULL) {
        queue->head = node;
    } else {
        queue->tail->next = node;
    }
    queue->tail = node;
}

bool isEmpty(struct Queue *queue) {
    if (queue->head == NULL) {
        return true;
    }
    return false;
}

int dequeue(struct Queue *queue) {
    if (isEmpty(queue)) {
        printf("Can't dequeue this queue\n");
        exit(EXIT_FAILURE);
    }

    struct Node *node = queue->head;

    queue->head = node->next;

    if (isEmpty(queue)) {
        queue->tail = NULL;
    }

    if (node != NULL) {
        int value = node->value;
        free(node);
        return value;
    }

    exit(EXIT_FAILURE);
}




int main() {
    struct Queue *queue = newQueue();

    enqueue(queue, 1);
    enqueue(queue, 2);
    enqueue(queue, 3);

    while (!isEmpty(queue)) {
        printf("Dequeueing %d \n", dequeue(queue));
    }

    exit(EXIT_SUCCESS);
}