C# | Get object at the top of the Stack – Peek operation
Stack represents a last-in, first out collection of object. It is used when you need a last-in, first-out access to items. When you add an item in the list, it is called pushing the item and when you remove it, it is called popping the item. Stack<T>.Peek Method is used to returns the object at the top of the Stack<T> without removing it. This method is an O(1) operation.
- The capacity of a Stack is the number of elements the Stack can hold. As elements are added to a Stack, the capacity is automatically increased as required through reallocation.
- If Count is less than the capacity of the stack, Push is an O(1) operation. If the capacity needs to be increased to accommodate the new element, Push becomes an O(n) operation, where n is Count. Pop is an O(1) operation.
- Stack accepts null as a valid value and allows duplicate elements.
Return Value: The Peek() method returns the last (top-most) value from the Stack<T> of type System.Object.
Exception: Calling Peek() method on empty stack will throw InvalidOperationException. So always check for elements in the stack before retrieving elements using the Peek() method.
Below given are some examples to understand the implementation in a better way.
Total number of elements in the Stack are : 6 Element at the top is : 6th Element Element at the top is : 6th Element Total number of elements in the Stack are : 6
System.InvalidOperationException: Stack empty.