Queue using linked list

// A C program to demonstrate linked list based implementation of queue 
#include <stdio.h> 
#include <stdlib.h> 

  
// A linked list (LL) node to store a queue entry 

struct QNode { 

    int key; 

    struct QNode* next; 
}; 

  
// The queue, front stores the front node of LL and rear stores the 
// last node of LL 

struct Queue { 

    struct QNode *front, *rear; 
}; 

  
// A utility function to create a new linked list node. 

struct QNode* newNode(int k) 
{ 

    struct QNode* temp = (struct QNode*)malloc(sizeof(struct QNode)); 

    temp->key = k; 

    temp->next = NULL; 

    return temp; 
} 

  
// A utility function to create an empty queue 

struct Queue* createQueue() 
{ 

    struct Queue* q = (struct Queue*)malloc(sizeof(struct Queue)); 

    q->front = q->rear = NULL; 

    return q; 
} 

  
// The function to add a key k to q 

void enQueue(struct Queue* q, int k) 
{ 

    // Create a new LL node 

    struct QNode* temp = newNode(k); 

  

    // If queue is empty, then new node is front and rear both 

    if (q->rear == NULL) { 

        q->front = q->rear = temp; 

        return; 

    } 

  

    // Add the new node at the end of queue and change rear 

    q->rear->next = temp; 

    q->rear = temp; 
} 

  
// Function to remove a key from given queue q 

void deQueue(struct Queue* q) 
{ 

    // If queue is empty, return NULL. 

    if (q->front == NULL) 

        return; 

  

    // Store previous front and move front one node ahead 

    struct QNode* temp = q->front; 

  

    q->front = q->front->next; 

  

    // If front becomes NULL, then change rear also as NULL 

    if (q->front == NULL) 

        q->rear = NULL; 

  

    free(temp); 
} 

  
// Driver Program to test anove functions 

int main() 
{ 

    struct Queue* q = createQueue(); 

    enQueue(q, 10); 

    enQueue(q, 20); 

    deQueue(q); 

    deQueue(q); 

    enQueue(q, 30); 

    enQueue(q, 40); 

    enQueue(q, 50); 

    deQueue(q); 

    printf("Queue Front : %d \n", q->front->key); 

    printf("Queue Rear : %d", q->rear->key); 

    return 0;