queue using linked list c 2b 2b

1/*
2 * Program  : Queue using linked list
3 * Language : C
4 */
5
6#include<stdio.h>
7#include<stdlib.h>
8
9struct node
10{
11    int data;
12    struct node *next;
13};
14
15struct node *front = NULL, *rear = NULL;
16
17void enqueue(int val)
18{
19    struct node *newNode = malloc(sizeof(struct node));
20    newNode->data = val;
21    newNode->next = NULL;
22
23    //if it is the first node
24    if(front == NULL && rear == NULL)
25        //make both front and rear points to the new node
26        front = rear = newNode;
27    else
28    {
29        //add newnode in rear->next
30        rear->next = newNode;
31
32        //make the new node as the rear node
33        rear = newNode;
34    }
35}
36
37void dequeue()
38{
39    //used to free the first node after dequeue
40    struct node *temp;
41
42    if(front == NULL)
43         printf("Queue is Empty. Unable to perform dequeue\n");
44    else
45    {
46        //take backup
47        temp = front;
48
49        //make the front node points to the next node
50        //logically removing the front element
51        front = front->next;
52
53        //if front == NULL, set rear = NULL
54        if(front == NULL)
55            rear = NULL;
56
57       //free the first node
58       free(temp);
59    }
60
61}
62
63void printList()
64{
65    struct node *temp = front;
66
67    while(temp)
68    {
69        printf("%d->",temp->data);
70        temp = temp->next;
71    }
72    printf("NULL\n");
73}
74
75int main()
76{
77    enqueue(10);
78    enqueue(20);
79    enqueue(30);
80    printf("Queue :");
81    printList();
82    dequeue();
83    printf("After dequeue the new Queue :");
84    printList();
85    dequeue();
86    printf("After dequeue the new Queue :");
87    printList();
88
89    return 0;
90}
91

1/*
2 * Program  : Queue using linked list
3 * Language : C
4 */
5
6#include<stdio.h>
7#include<stdlib.h>
8
9struct node
10{
11    int data;
12    struct node *next;
13};
14
15struct node *front = NULL, *rear = NULL;
16
17void enqueue(int val)
18{
19    struct node *newNode = malloc(sizeof(struct node));
20    newNode->data = val;
21    newNode->next = NULL;
22
23    //if it is the first node
24    if(front == NULL && rear == NULL)
25        //make both front and rear points to the new node
26        front = rear = newNode;
27    else
28    {
29        //add newnode in rear->next
30        rear->next = newNode;
31
32        //make the new node as the rear node
33        rear = newNode;
34    }
35}
36
37void dequeue()
38{
39    //used to free the first node after dequeue
40    struct node *temp;
41
42    if(front == NULL)
43         printf("Queue is Empty. Unable to perform dequeue\n");
44    else
45    {
46        //take backup
47        temp = front;
48
49        //make the front node points to the next node
50        //logically removing the front element
51        front = front->next;
52
53        //if front == NULL, set rear = NULL
54        if(front == NULL)
55            rear = NULL;
56
57       //free the first node
58       free(temp);
59    }
60
61}
62
63void printList()
64{
65    struct node *temp = front;
66
67    while(temp)
68    {
69        printf("%d->",temp->data);
70        temp = temp->next;
71    }
72    printf("NULL\n");
73}
74
75int main()
76{
77    enqueue(10);
78    enqueue(20);
79    enqueue(30);
80    printf("Queue :");
81    printList();
82    dequeue();
83    printf("After dequeue the new Queue :");
84    printList();
85    dequeue();
86    printf("After dequeue the new Queue :");
87    printList();
88
89    return 0;
90}