Stack Implementation in C Using Linked List (With Code & Explanation)

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Why Use Linked List for Stack?

Unlike arrays, a stack implemented with a linked list does not have a fixed size and can grow or shrink as needed during runtime. This makes it more memory efficient.

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Stack Operations

Operation	Description
PUSH	Insert an element at the top of the stack
POP	Remove the top element from the stack
DISPLAY	View the stack from top to bottom

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C Program: Stack Using Linked List

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

// Structure for a stack node
struct Node {
    int data;
    struct Node* next;
};

struct Node* top = NULL;

// PUSH operation
void push(int value) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    if (!newNode) {
        printf("Memory allocation failed\n");
        return;
    }
    newNode->data = value;
    newNode->next = top;
    top = newNode;
    printf("%d pushed to stack\n", value);
}

// POP operation
void pop() {
    if (top == NULL) {
        printf("Stack Underflow\n");
        return;
    }
    struct Node* temp = top;
    printf("%d popped from stack\n", top->data);
    top = top->next;
    free(temp);
}

// DISPLAY operation
void display() {
    if (top == NULL) {
        printf("Stack is empty\n");
        return;
    }
    struct Node* temp = top;
    printf("Stack elements: ");
    while (temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}

// Main function
int main() {
    int choice, value;
    do {
        printf("\nMenu:\n1. PUSH\n2. POP\n3. DISPLAY\n4. EXIT\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                printf("Enter value to push: ");
                scanf("%d", &value);
                push(value);
                break;
            case 2:
                pop();
                break;
            case 3:
                display();
                break;
            case 4:
                printf("Exiting program...\n");
                break;
            default:
                printf("Invalid choice. Try again.\n");
        }
    } while (choice != 4);
    return 0;
}

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Output Example

Menu:
1. PUSH
2. POP
3. DISPLAY
4. EXIT

Enter your choice: 1
Enter value to push: 10
10 pushed to stack

Enter your choice: 1
Enter value to push: 20
20 pushed to stack

Enter your choice: 3
Stack elements: 20 -> 10 -> NULL

Enter your choice: 2
20 popped from stack

Enter your choice: 3
Stack elements: 10 -> NULL

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Key Benefits of Linked List Stack

• No overflow unless system memory is full.
• Dynamic memory allocation.
• Efficient for applications requiring dynamic stacks (e.g., recursion tracking, undo functionality).