A stack is a fundamental data structure in computer science used to manage data in a last-in, first-out (LIFO) manner. In this comprehensive guide, we will explore how to implement a stack using a linked list in the C programming language. Linked list-based stacks are dynamic and can grow or shrink as needed, making them a versatile choice for various applications.

Table of Contents

1. Introduction to Stacks

• What is a Stack?
• Why Use a Linked List-Based Stack?

1. Basics of Linked Lists

• Understanding Linked Lists
• Advantages of Using Linked Lists

1. Implementing a Stack with Linked List

• Designing the Stack Structure
• Stack Operations
• Handling Overflow and Underflow

1. Code Example: Stack Using Linked List in C

• Code Walkthrough
• Compilation and Execution

1. Applications of Stack Using Linked List

• Where Linked List-Based Stacks Shine

1. Advantages and Disadvantages

• Pros and Cons of Linked List-Based Stacks

1. Conclusion

1. Introduction to Stacks

What is a Stack?

A stack is a linear data structure that follows the LIFO (Last-In, First-Out) principle. This means that the last element added to the stack is the first one to be removed. Stacks are widely used in computer science and are essential in various algorithms and applications, such as function call management, expression evaluation, and parsing.

Why Use a Linked List-Based Stack?

In C, you have the option to implement a stack using various data structures, including arrays. However, a linked list-based stack offers several advantages:

• Dynamic Size: Linked lists can grow or shrink dynamically, allowing the stack to adapt to changing requirements.
• No Fixed Size Limit: Unlike arrays, linked lists do not have a fixed size limit, making them suitable for situations where the stack’s size is unknown or can vary.
• Efficient Insertion and Deletion: Linked lists excel in inserting and deleting elements, making push and pop operations on the stack efficient.
• Memory Efficiency: Linked list-based stacks allocate memory dynamically, utilizing memory more efficiently than fixed-size arrays.

2. Basics of Linked Lists

Understanding Linked Lists

A linked list is a data structure consisting of nodes, where each node contains data and a reference (or pointer) to the next node in the sequence. Linked lists come in various forms, including singly linked lists, doubly linked lists, and circular linked lists. In the context of implementing a stack, a singly linked list is often preferred.

Advantages of Using Linked Lists

Linked lists offer several advantages:

• Dynamic Size: Linked lists can grow or shrink as needed, accommodating variable-sized data.
• Efficient Insertions and Deletions: Inserting or deleting elements in a linked list is efficient, especially when compared to arrays.
• Memory Efficiency: Linked lists allocate memory dynamically, reducing wasted memory.
• Versatility: Different types of linked lists can be used for various applications, including stacks.

3. Implementing a Stack with Linked List

Designing the Stack Structure

To implement a stack using a linked list in C, you need to define the structure of a node and the stack itself. Each node should contain a data element and a pointer to the next node in the stack. The stack structure should keep track of the top element and may include other metadata, such as the size of the stack.

Stack Operations

A stack supports the following fundamental operations:

• Push: Add an element to the top of the stack.
• Pop: Remove the top element from the stack.
• Peek (or Top): Retrieve the top element without removing it.
• IsEmpty: Check if the stack is empty.
• Size: Get the number of elements in the stack.

Handling Overflow and Underflow

In a linked list-based stack, you should be aware of two potential issues:

• Stack Overflow: Occurs when you try to push an element onto a stack that has reached its memory limit.
• Stack Underflow: Occurs when you try to pop an element from an empty stack.

Properly handling these situations is crucial to ensure the robustness of your stack implementation.

4. Code Example: Stack Using Linked List in C

Let’s dive into a code example that demonstrates how to implement a stack using a singly linked list in C. We will walk through the code, step by step, and explain each part of the implementation.

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

// Define the structure of a stack node
struct Node {
    int data;
    struct Node* next;
};

// Define the structure of a stack
struct Stack {
    struct Node* top;
    unsigned int size;
};

// Function to create an empty stack
struct Stack* createStack() {
    struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
    stack->top = NULL;
    stack->size = 0;
    return stack;
}

// Function to check if the stack is empty
int isEmpty(struct Stack* stack) {
    return (stack->top == NULL);
}

// Function to push an element onto the stack
void push(struct Stack* stack, int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = stack->top;
    stack->top = newNode;
    stack->size++;
}

// Function to pop an element from the stack
int pop(struct Stack* stack) {
    if (isEmpty(stack)) {
        printf("Stack underflow!\n");
        return -1; // Return a sentinel value to indicate underflow
    }
    struct Node* temp = stack->top;
    int poppedData = temp->data;
    stack->top = temp->next;
    free(temp);
    stack->size--;
    return poppedData;
}

// Function to peek the top element of the stack
int peek(struct Stack* stack) {
    if (isEmpty(stack)) {
        printf("Stack is empty!\n");
        return -1; // Return a sentinel value to indicate empty stack
    }
    return stack->top->data;
}

// Function to get the size of the stack
unsigned int getSize(struct Stack* stack) {
    return stack->size;
}

// Driver program to test the stack implementation
int main() {
    struct Stack* stack = createStack();

    push(stack, 10);
    push(stack, 20);
    push(stack, 30);

    printf("Top element: %d\n", peek(stack));
    printf("Stack

 size: %u\n", getSize(stack));

    printf("Popped element: %d\n", pop(stack));
    printf("Popped element: %d\n", pop(stack));

    printf("Stack size: %u\n", getSize(stack));

    return 0;
}

In this code example, we define the structures for stack nodes and the stack itself. We implement functions for stack creation, push, pop, peek, isEmpty, and getSize. The main function demonstrates how to use the stack implementation.

5. Applications of Stack Using Linked List

Linked list-based stacks find applications in various scenarios, including:

• Expression Evaluation: Stacks help evaluate mathematical expressions, such as infix, postfix, or prefix expressions.
• Function Call Management: Stacks are used to manage function calls and their local variables.
• Parsing: Stacks are employed in parsing and syntax analysis of programming languages.

6. Advantages and Disadvantages

Pros of Linked List-Based Stacks

• Dynamic Size: Linked list-based stacks can grow or shrink as needed.
• Efficient Insertions and Deletions: Push and pop operations are efficient.
• Memory Efficiency: Memory is allocated dynamically, reducing waste.

Cons of Linked List-Based Stacks

• Additional Memory Overhead: Each node requires extra memory for the pointer.
• Slower Random Access: Accessing elements by index is slower compared to arrays.

7. Conclusion

Implementing a stack using a linked list in C provides a dynamic and memory-efficient solution for managing data in a last-in, first-out manner. Understanding the principles of stacks and linked lists is essential for building robust and efficient software, as these data structures are widely used in various applications.

By mastering the implementation of a stack using a linked list, you gain valuable insights into data structure design and memory management, making you a more proficient C programmer. Consider practicing and exploring further applications of this fundamental data structure to enhance your programming skills.