23. Linear Queue Using Linked List The One Where Rahul Says “Dynamic Problems Need Dynamic Solutions”

     

hello everyone 

Today felt like one of those days where the actual code was calm but the DSU friend group? pure chaotic. We had to write a C program for: “insert and delete operations on a Linear Queue using a Linked List.” And trust me this was the perfect topic for our gang.

Scene 1: The “Array Queue Trauma” Flashback

As soon as sir said Linked List Queue, Aarav screamed: “finally! No more overflow! My trauma is healed!” Rahul looked at him the same way you look at someone who says “WiFi not working? Restart the whole society.” He calmly replied: “Aarav overflow still happens. RAM doesn’t grow on trees.” Me (Daksh) silently started writing the blog title.

What Makes Linked List Queue Different?

Here’s what our little DSU gang discovered:

1. Every node holds data + a pointer

2. A new element always goes to the rear

3. Deletion always happens at the front (FIFO forever!)

4. Memory is dynamic, so no fixed size like arrays

5. frontNode - first element

6. rearNode - last element

Aarav called this: “Queue with unlimited storage. Basically my 230 GB WhatsApp backup.”

No comments.

Division of Responsibilities (aka “Why We Always Fight”)

Rahul – The Rear Gatekeeper

He handled INSERT operations. He kept saying: “If you want to enter, go behind everyone” and glared at Aarav.

Aarav – The Accidental Front Bouncer

He handled DELETE. But he kept trying to delete from the rear too. Rahul snapped: “DUDE, THIS IS NOT A STACK. FRONT MEANS FRONT.” Aarav: “Then why isn't it called FRONTSTACK???” Me: deeply questioning my life choices.

Me (Daksh) – Display + Peacekeeper

I displayed the queue after each operation.

Why?

• No array size limits

• No shifting of elements

• Efficient for dynamic input

• Perfect for unpredictable workloads

• And perfect for unpredictable friends like Aarav

Code:

 #define _CRT_SECURE_NO_WARNINGS
 #include <stdio.h>
 #include <stdlib.h>
 struct Node {
     int dataValue;
     struct Node* nextNode;
 };
 struct Node* frontNode = NULL;
 struct Node* rearNode = NULL;
 void insertElement(int value) {
     struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
     newNode->dataValue = value;
     newNode->nextNode = NULL;
     if (rearNode == NULL) {
         frontNode = rearNode = newNode;
     } else {
         rearNode->nextNode = newNode;
         rearNode = newNode;
     }
     printf("Inserted %d into the queue.\n", value);
 }
 void deleteElement() {
     if (frontNode == NULL) {
         printf("Queue Underflow! No elements to delete.\n");
         return;
     }
     struct Node* temporaryNode = frontNode;
     printf("Deleted %d from the queue.\n", frontNode->dataValue);
     frontNode = frontNode->nextNode;
     if (frontNode == NULL)
         rearNode = NULL;
     free(temporaryNode);
 }
 void displayQueue() {
     if (frontNode == NULL) {
         printf("Queue is empty.\n");
         return;
     }
     struct Node* currentNode = frontNode;
     printf("Queue elements are: ");
     while (currentNode != NULL) {
         printf("%d ", currentNode->dataValue);
         currentNode = currentNode->nextNode;
     }
     printf("\n");
 }
 int main() {
     int userChoice, elementValue;
     char userDecision;
     do {
         printf("\n--- Linear Queue Using Linked List ---\n");
         printf("1. Insert Element\n2. Delete Element\n3. Display Queue\n");
         printf("Enter your choice: ");
         scanf("%d", &userChoice);
         switch (userChoice) {
             case 1:
                 printf("Enter value to insert: ");
                 scanf("%d", &elementValue);
                 insertElement(elementValue);
                 break;
             case 2:
                 deleteElement();
                 break;
             case 3:
                 displayQueue();
                 break;
             default:
                 printf("Invalid choice.\n");
         }
         printf("\nDo you want to continue or quit? (y/n): ");
         scanf(" %c", &userDecision);
     } while (userDecision == 'y' || userDecision == 'Y');
     printf("Program ended.\n");
     return 0;
 }

Output:

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