C# | Create a Stack from a collection

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. Creation of stack means the addition of item into the stack. Stack<T>.Push(Object) Method is used to Inserts an object at the top of the Stack.

Properties:

  • 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.

Syntax:

public virtual void Push (object obj);

Parameter:

obj: The Object of type System.Object which is to push onto the Stack<T>. The value can be null.



Below given are some examples to understand the implementation in a better way :

Example 1:

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// C# code to Create a Stack
// from a collection
using System;
using System.Collections.Generic;
  
class GFG {
    // Driver code
    public static void Main()
    {
        // Creating a Stack of strings
        Stack<string> myStack1 = new Stack<string>();
  
        // Inserting the elements into the Stack
        myStack1.Push("GeeksforGeeks");
        myStack1.Push("is");
        myStack1.Push("the");
        myStack1.Push("best");
        myStack1.Push("website");
  
        // Displaying the count of elements
        // contained in the myStack1
        Console.Write("Total number of elements in the Stack 1 are : ");
  
        Console.WriteLine(myStack1.Count);
  
        // Displaying the elements in Stack myStack1
        foreach(string str in myStack1)
        {
            Console.WriteLine(str);
        }
  
        // Creating a Stack from a collection
        Stack<string> myStack2 = new Stack<string>(myStack1.ToArray());
  
        // Displaying the count of elements
        // contained in the myStack2
        Console.Write("Total number of elements in the Stack 2 are : ");
  
        Console.WriteLine(myStack2.Count);
  
        // Displaying the elements in Stack myStack2
        foreach(string str in myStack2)
        {
            Console.WriteLine(str);
        }
    }
}

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Output:

Total number of elements in the Stack 1 are : 5
website
best
the
is
GeeksforGeeks
Total number of elements in the Stack 2 are : 5
GeeksforGeeks
is
the
best
website

Example 2:

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// C# code to Create a Stack
// from a collection
using System;
using System.Collections.Generic;
  
class GFG {
    // Driver code
    public static void Main()
    {
        // Creating a Stack of Integers
        Stack<int> myStack1 = new Stack<int>();
  
        // Inserting the elements into the Stack
        myStack1.Push(5);
        myStack1.Push(10);
        myStack1.Push(15);
        myStack1.Push(20);
        myStack1.Push(25);
  
        // Displaying the count of elements
        // contained in the myStack1
        Console.Write("Total number of elements in the Stack 1 are : ");
  
        Console.WriteLine(myStack1.Count);
  
        // Displaying the elements in Stack myStack1
        foreach(int i in myStack1)
        {
            Console.WriteLine(i);
        }
  
        // Creating a Stack from a collection
        Stack<int> myStack2 = new Stack<int>(myStack1.ToArray());
  
        // Displaying the count of elements
        // contained in the myStack2
        Console.Write("Total number of elements in the Stack 2 are : ");
  
        Console.WriteLine(myStack2.Count);
  
        // Displaying the elements in Stack myStack2
        foreach(int i in myStack2)
        {
            Console.WriteLine(i);
        }
    }
}

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Output:

Total number of elements in the Stack 1 are : 5
25
20
15
10
5
Total number of elements in the Stack 2 are : 5
5
10
15
20
25

Reference: https://docs.microsoft.com/en-us/dotnet/api/system.collections.stack.push?view=netframework-4.7.2



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