Stack implementation in c#

Question

I'm just posting how to implement stack in c#... I hope someone finds it helpfull

Answer 1

Console.WriteLine("Hello, World!");
Stack stack = new();
stack.Push(4);
stack.Push(2);
stack.Push(0);
stack.Push(420);
stack.Push(69);
stack.Push(42069);
stack.Peek();
Console.WriteLine($"Item popped: {stack.Pop()}");
Console.WriteLine();
stack.PrintAll();


internal class Stack
{
    // length of array
    static readonly int max = 1000;
    int top;
    // array of ints of specified length
    int[] stack = new int[max];

    public Stack()
    {
        this.top = -1;
    }

    bool isEmpty()
    {
        return (top < 0);
    }

    // method for adding data
    internal bool Push(int data)
    {
        // if is arrray already full, returns false, else sets new value as top value
        if (this.top >= max)
        {
            Console.WriteLine("Stack Overflow");
            return false;
        }
        else
        {
            stack[++this.top] = data;
            return true;
        }
    }

    // method to remove last element in stack
    internal int? Pop()
    {
        // if is stack empty, returns nothing, else returns last value
        if (this.isEmpty())
        {
            Console.WriteLine("Stack Underflow");
            return null;
        }
        else
        {
            int value = stack[this.top--];
            return value;
        }
    }

    // method to return last element in stack
    internal void Peek()
    {
        // if is stack empty, returns nothing, else returns last value
        if (this.isEmpty())
        {
            Console.WriteLine("Stack Underflow");
            return;
        }
        else
        {
            Console.WriteLine($"The topmost element of stack is {stack[top]}");
        }
    }
    // method to print all elements in stack
    internal void PrintAll()
    {
        if (this.isEmpty())
        {
            Console.WriteLine("The array is empty");
            return;
        }
        else
        {
            Console.WriteLine("Items of stack are: ");
            for (int i = top; i >= 0; i--)
            {
                Console.WriteLine(stack[i]);
            }
        }
    }
}

Answer 2

.net already implemented a generic stack.

https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.stack-1?view=net-7.0.

Also it dynamically resizes the backing array so it not limited in size. For learning you might refactor to generic and handle size allocations.

dotnet reference source:

https://github.com/microsoft/referencesource/blob/master/System/compmod/system/collections/generic/stack.cs

dotnet core source: https://github.com/dotnet/runtime/blob/main/src/libraries/System.Collections/src/System/Collections/Generic/Stack.cs