Cpp_Exp18_Stack-Implementation-using-Array

📘 Experiment: Stack Implementation Using Arrays in C++

---

🎯 AIM

To implement a stack data structure using arrays in C++ and perform basic operations such as push, pop, peek, and display.

---

📌 OBJECTIVES

• To understand the concept of a stack as a linear data structure.
• To learn how to use arrays and classes in C++ for implementing abstract data types.
• To practice error handling for stack overflow and underflow conditions.
• To develop logic-building skills by writing step-by-step algorithms.
• To understand how LIFO (Last In, First Out) principle is applied in computing.

---

📖 THEORY

🔹 What is a Stack?

A stack is a linear data structure that follows LIFO (Last In, First Out):

• The element inserted last is removed first.
• Example: Stack of books – only the top book can be removed or added.

🔹 Basic Stack Operations

• Push → Insert an element at the top.
• Pop → Remove the top element.
• Peek/Top → View the top element without removing it.
• Display → Show all elements in the stack.

🔹 Real-Life Examples

• Undo/Redo operations in editors.
• Backtracking in puzzles (e.g., maze solving).
• Function calls in programming (call stack).
• Browser history (Back button).

🔹 Overflow and Underflow

• Overflow → Stack is full and cannot insert new elements.
• Underflow → Stack is empty and cannot remove/peek elements.

🔹 Comparison: Array vs Linked List Stack

Feature	Array-based Stack	Linked-list-based Stack
Memory Allocation	Fixed size (MAX_SIZE)	Dynamic, grows/shrinks
Speed	Fast (direct indexing)	Slightly slower (pointer ops)
Memory Usage	May waste space	Exact memory but extra for ptr
Implementation	Simple and easy	More complex

---

⚙️ ALGORITHMS

🔹 Stack Function (Array Approach)

push()

1. Increment top by 1.
2. Assign the value to array[top].
3. Return the inserted element.

Main Program

1. Initialize integer array array[5] and top = -1.
2. Use a loop to push elements 5 times.
3. Print inserted elements.

---

🔹 Stack Class Approach

pushElement(num)

1. Check if topIndex == MAX_SIZE - 1.
2. If yes → print STACK OVERFLOW.
3. Else → increment topIndex and insert num.

popElement()

1. If topIndex == -1 → print STACK UNDERFLOW.
2. Else → return arr[topIndex] and decrement topIndex.

peekTop()

1. If topIndex == -1 → print STACK UNDERFLOW.
2. Else → return arr[topIndex].

displayStack()

1. If topIndex == -1 → print STACK UNDERFLOW.
2. Else → print all elements from index 0 to topIndex.

---

📝 PROGRAM DESCRIPTION

🔹 Stack Function

• Uses array[5] and top to track the stack.
• push() inserts value 77 at the top.
• Main function calls push() 5 times.
• Uses pass-by-reference for top to update the main stack.

🔹 Stack Class

• Private data:
  • arr[MAX_SIZE] → Stores stack elements.
  • topIndex → Tracks top element.
• Public functions:
  • pushElement(int num) → Insert element.
  • popElement() → Remove top element.
  • peekTop() → View top element.
  • displayStack() → Display all elements.
• Main function demonstrates push, pop, peek, display operations.

---

🧩 CONCEPTS USED

• Class & Object → Encapsulation of stack operations.
• Array → Stores elements sequentially.
• Encapsulation → Access stack via methods only.
• Conditionals (if-else) → Handle overflow/underflow.
• Loops (for loop) → Display stack elements.
• Macros (#define) → For constants like MAX_SIZE and ERROR_CODE.

---

✅ CONCLUSION

• Successfully implemented a stack using arrays in C++.
• Demonstrated push, pop, peek, display operations.
• Showed array-based vs linked-list-based stack differences.
• Improved understanding of data structures, OOP, and error handling.
• Stack is fundamental in compilers, operating systems, and problem-solving applications.