static void Main(string[] args)
{
// Stack - A LIFO collection
Stack<string> stack = new Stack<string>();
stack.Push("A"); // Push adds to the stack
stack.Push("B");
stack.Push("C");
stack.Push("D");
Console.WriteLine(stack.Peek()); // D - Peek returns the last added value without removing it
Console.WriteLine(stack.Pop()); // D - Pop returna the last added value and removes it
Console.WriteLine(stack.Peek()); // C
// Queue - A FIFO collection
Queue<string> queue = new Queue<string>();
queue.Enqueue("a"); // Enqueue adds to the queue
queue.Enqueue("b");
queue.Enqueue("c");
queue.Enqueue("d");
Console.WriteLine(queue.Peek()); // a - Peek returns the beginning value without removing it
Console.WriteLine(queue.Dequeue()); // a - Dequeue returns the beginning value and removes it
Console.WriteLine(queue.Peek()); // b
//--
Console.ReadKey();
}
