What Is Meant by Stack in Data Structure?

What Is Meant by Stack in Data Structure?

A stack is a fundamental data structure in computer science that follows the Last In First Out (LIFO) principle. It can be visualized as a stack of plates where the last plate placed on top is the first one to be removed.

Basic Operations on a Stack

A stack supports three main operations:

• Push: This operation adds an element to the top of the stack. The new element becomes the top of the stack, and all other elements shift down.
• Pop: This operation removes and returns the element from the top of the stack. The next element becomes the new top.
• Peek (or Top): This operation returns the element at the top of the stack without removing it.

Implementing a Stack

A stack can be implemented using various programming languages. Here’s an example of implementing a stack using JavaScript:

<script>
class Stack {
  constructor() {
    this.stack = [];
  }
  
  push(element) {
    this.stack.push(element);
  }
  
  pop() {
    if (this.isEmpty()) {
      return "Stack Underflow";
    }
    return this.pop();
  }
  
  peek() {
    if (this.isEmpty()) {
      return "Stack is empty";
    }
    return this.stack[this.length - 1];
  }
  
  isEmpty() {
    return this.length === 0;
  }
}

// Example usage
const myStack = new Stack();
myStack.push(10);
myStack.push(20);
console.log(myStack.peek()); // Output: 20
console.pop()); // Output: 20
</script>

Applications of Stacks

Stacks are used in various real-world applications, including:

• Function Call Stack: Stacks are used to manage function calls within a program, keeping track of the order in which functions are called and return from.
• Undo/Redo Operations: Stacks can be used to implement undo and redo functionality in applications.
• Expression Evaluation: Stacks are utilized to evaluate arithmetic expressions, converting them from infix notation to postfix or prefix notation.
• Backtracking Algorithms: Stacks play a crucial role in backtracking algorithms, such as depth-first search.

In Conclusion

A stack is an essential data structure that follows the Last In First Out principle. It supports operations like push, pop, and peek.

Implementing a stack involves using the appropriate programming language syntax. Stacks have various real-world applications and are widely used in computer science and software development.