Queue Using Linked List

Order Of Programs.md

@@ -32,3 +32,4 @@
 |30        | SelectionSort.c | SelectionSort.exe | WAP to sort an array using selection sort |
 |31        | StackUsingLinkedList.c | StackUsingLinkedList.exe | WAP to Implement a Stack using Linked List |
 |32        | SinglyLinkedList.c | SinglyLinkedList.exe | WAP to implement singly linked lists |
+|33        | QueueUsingLinkedList.c | QueueUsingLinkedList.exe | WAP to implement a Queue using Linked List |

QueueUsingLinkedList.c

@@ -0,0 +1,106 @@
+// WAP to implement Queue using linked list.
+
+#include<stdio.h>   
+#include<stdlib.h>  
+
+struct node   
+{  
+    int data;   
+    struct node *next;  
+};  
+struct node *front;  
+struct node *rear;   
+void insert();  
+void delete();  
+void display();  
+void main ()  
+{  
+    int choice;   
+    while(choice != 4)   
+    {     
+        printf("\n*************************Main Menu*****************************\n");  
+        printf("\n=================================================================\n");  
+        printf("\n1.insert an element\n2.Delete an element\n3.Display the queue\n4.Exit\n");  
+        printf("\nEnter your choice ?");  
+        scanf("%d",& choice);  
+        switch(choice)  
+        {  
+            case 1:  
+            insert();  
+            break;  
+            case 2:  
+            delete();  
+            break;  
+            case 3:  
+            display();  
+            break;  
+            case 4:  
+            exit(0);  
+            break;  
+            default:   
+            printf("\nEnter valid choice??\n");  
+        }  
+    }  
+}  
+void insert()  
+{  
+    struct node *ptr;  
+    int item;
+    ptr = (struct node *) malloc (sizeof(struct node));  
+    if(ptr == NULL)  
+    {  
+        printf("\nOVERFLOW\n");  
+        return;  
+    }  
+    else  
+    {   
+        printf("\nEnter value?\n");  
+        scanf("%d",&item);  
+        ptr -> data = item;  
+        if(front == NULL)  
+        {  
+            front = ptr;  
+            rear = ptr;   
+            front -> next = NULL;  
+            rear -> next = NULL;  
+        }  
+        else   
+        {  
+            rear -> next = ptr;  
+            rear = ptr;  
+            rear->next = NULL;  
+        }  
+    }  
+}     
+void delete ()  
+{  
+    struct node *ptr;  
+    if(front == NULL)  
+    {  
+        printf("\nUNDERFLOW\n");  
+        return;  
+    }  
+    else   
+    {  
+        ptr = front;  
+        front = front -> next;  
+        free(ptr);  
+    }  
+}  
+void display()  
+{  
+    struct node *ptr;  
+    ptr = front;      
+    if(front == NULL)  
+    {  
+        printf("\nEmpty queue\n");  
+    }  
+    else  
+    {   printf("\nprinting values .....\n");  
+        while(ptr != NULL)   
+        {  
+            printf("\n%d\n",ptr -> data);  
+            ptr = ptr -> next;  
+        }  
+    }  
+}