Implementing Stack in C#

Stack is a linear data structure. It follows LIFO(Last In First Out) pattern for Input/output. Following three basic operations are performed in the stack:

• Push: Adds an item in the stack. If the stack is full, then it is said to be a stack Overflow condition.
• Pop: Removes an item from the stack. The items are popped in the reversed order in which they are pushed. If the stack is empty, then it is said to be a stack Underflow condition.
• Peek : Return the topmost element of stack.

Given below is the C# code to implement Stack using Arrays

using System;

namespace StackImplementation
{
    internal class Stack
    {
        static readonly int MAX = 1000;
        int top;
        int[] stack = new int[MAX];

        bool IsEmpty()
        {
            return (top < 0);
        }
        public Stack()
        {
            top = -1;
        }
        internal bool Push(int data)
        {
            if (top >= MAX)
            {
                Console.WriteLine("Stack Overflow");
                return false;
            }
            else
            {
                stack[++top] = data;
                return true;
            }
        }

        internal int Pop()
        {
            if (top < 0)
            {
                Console.WriteLine("Stack Underflow");
                return 0;
            }
            else
            {
                int value = stack[top--];
                return value;
            }
        }

        internal void Peek()
        {
            if (top < 0)
            {
                Console.WriteLine("Stack Underflow");
                return;
            }
            else
                Console.WriteLine("The topmost element of Stack is : {0}", stack[top]);
        }

        internal void PrintStack()
        {
            if (top < 0)
            {
                Console.WriteLine("Stack Underflow");
                return;
            }
            else
            {
                Console.WriteLine("Items in the Stack are :");
                for (int i = top; i >= 0; i--)
                {
                    Console.WriteLine(stack[i]);
                }
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Stack myStack = new Stack();

            myStack.Push(10);
            myStack.Push(20);
            myStack.Push(30);
            myStack.Push(40);
            myStack.PrintStack();
            myStack.Peek();
            Console.WriteLine("Item popped from Stack : {0}", myStack.Pop());
            myStack.PrintStack();
        }
    }
}

Output:

Items in the Stack are :
40
30
20
10
The topmost element of Stack is : 40
Item popped from Stack : 40
Items in the Stack are :
30
20
10

This article is contributed by Ankit Sharma. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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