Welcome to our exploration of the stack data structure. A stack is a linear data structure that follows the Last-In, First-Out principle, also known as LIFO. Think of it like a stack of plates in a cafeteria. You can only add new plates to the top of the stack, and when you need a plate, you take it from the top. The last plate placed on the stack is the first one to be removed.
Now let's explore the core operations of a stack. The most fundamental operations are Push and Pop. Push adds a new element to the top of the stack. Pop removes the top element and returns it. We also have Peek or Top operation which lets us view the top element without removing it. IsEmpty checks if the stack has no elements, and IsFull checks if the stack has reached its maximum capacity.
Let's demonstrate push and pop operations step by step. We start with an empty stack. First, we push the value 5 onto the stack. Then we push 10, which goes on top of 5. Next, we push 15, which becomes the new top element. Now let's pop elements. Pop removes 15 first, since it was the last element added. Another pop removes 10, leaving only 5 in the stack.
Stacks have numerous practical applications in computer science and everyday software. The function call stack manages how programs execute functions - when a function is called, it's pushed onto the stack, and when it returns, it's popped off. Expression evaluation uses stacks to parse mathematical expressions correctly. Undo and redo operations in text editors and image editors rely on stacks to remember previous states. Even your browser's back button uses a stack to track your browsing history.
To summarize what we've learned about stacks: A stack is a fundamental data structure that follows the Last-In, First-Out principle. The core operations include Push to add elements, Pop to remove elements, and Peek to view the top element. Stacks are widely used in programming for function call management, expression evaluation, and implementing undo functionality. Understanding stacks is essential for any programmer as they form the foundation for many algorithms and system operations.