Understanding the Stack Data Structure

A comprehensive overview of stacks, their operations, and real-world applications.

What is a Stack?

A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. Elements are added and removed from the top of the stack.

Stack Operations

Push: Adds an element to the top of the stack.
Pop: Removes the top element from the stack.
Peek: Returns the top element without removing it.
isEmpty: Checks if the stack is empty.
isFull: Checks if the stack is full (in case of a bounded stack).

Examples of Stack in Action

Some common examples of stack usage:

Undo functionality in text editors.
Backtracking in maze solving algorithms.
Function call stack in programming.

Real-World Applications

Stacks are widely used in various computing contexts:

Browser history navigation.
Expression evaluation and syntax parsing.
Managing recursive function calls.

Stack Code Implementation

                    // C code for Stack Implementation
#include <stdio.h>
#include <stdlib.h>

#define MAX 100

struct Stack {
    int items[MAX];
    int top;
};

void initStack(struct Stack* stack) {
    stack->top = -1;
}

int isFull(struct Stack* stack) {
    return stack->top == MAX - 1;
}

int isEmpty(struct Stack* stack) {
    return stack->top == -1;
}

void push(struct Stack* stack, int element) {
    if (isFull(stack)) {
        printf("Stack Overflow\n");
    } else {
        stack->items[++stack->top] = element;
    }
}

int pop(struct Stack* stack) {
    if (isEmpty(stack)) {
        printf("Stack Underflow\n");
        return -1;
    } else {
        return stack->items[stack->top--];
    }
}

int peek(struct Stack* stack) {
    if (isEmpty(stack)) {
        printf("Stack is empty\n");
        return -1;
    } else {
        return stack->items[stack->top];
    }
}

int main() {
    struct Stack stack;
    initStack(&stack);
    push(&stack, 10);
    push(&stack, 20);
    printf("Top element: %d\n", peek(&stack));
    pop(&stack);
    printf("Top element after pop: %d\n", peek(&stack));
    return 0;
}