Remove all objects from the Stack in C#

Using Clear() with String Stack

Example

using System;
using System.Collections.Generic;

public class Demo {
    public static void Main(){
        Stack<string> stack = new Stack<string>();
        stack.Push("A");
        stack.Push("B");
        stack.Push("C");
        stack.Push("D");
        stack.Push("E");
        stack.Push("F");
        stack.Push("G");
        stack.Push("H");
        Console.WriteLine("Count of elements = "+stack.Count);
        Console.WriteLine("Elements in Stack...");
        foreach (string res in stack){
            Console.WriteLine(res);
        }
        stack.Clear();
        Console.Write("Count of elements (updated) = "+stack.Count);
    }
}

The output of the above code is −

Count of elements = 8
Elements in Stack...
H
G
F
E
D
C
B
A
Count of elements (updated) = 0

Using Clear() with Integer Stack

Example

using System;
using System.Collections.Generic;

public class Demo {
    public static void Main(){
        Stack<int> stack = new Stack<int>();
        stack.Push(10);
        stack.Push(20);
        stack.Push(30);
        stack.Push(40);
        stack.Push(50);
        stack.Push(60);
        stack.Push(70);
        stack.Push(80);
        stack.Push(90);
        stack.Push(100);
        Console.WriteLine("Count of elements = "+stack.Count);
        Console.WriteLine("Elements in Stack...");
        foreach (int res in stack){
            Console.WriteLine(res);
        }
        stack.Clear();
        Console.Write("Count of elements (updated) = "+stack.Count);
    }
}

The output of the above code is −

Count of elements = 10
Elements in Stack...
100
90
80
70
60
50
40
30
20
10
Count of elements (updated) = 0

Key Points

• The Clear() method removes all elements in O(1) time complexity.

• After calling Clear(), the Stack's Count property returns zero.

• The method does not throw any exceptions, even if the Stack is already empty.

• Memory used by the elements is eligible for garbage collection after clearing.

Conclusion

The Clear() method is the most efficient way to remove all objects from a Stack in C#. It immediately empties the Stack and sets its count to zero, making it ready for new elements to be pushed.