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VB.NET Stack TypeUse the Stack type to push and pop elements at the top of a collection.
dot net perls
Stack. A Stack adds elements to its top. Elements are pushed to the top, and then popped from the top. In these examples, we see how to loop over a VB.NET Stack, push and pop elements, and also peek and count.
Queue
LIFO The last element added to the Stack is the first element removed from the Stack. All activity occurs on the top of the stack.
Example. This example shows how to repeatedly Push elements to the top of a Stack. Then, we use the For-Each loop to display the Stack in the order from first to last. The most recently added element (1000) is at the top of the Stack.
For Each, For
Example 2. This example introduces the Pop and Peek functions on the Stack. With Pop, you take the top element off of the Stack and it is stored in the return value. It is no longer is part the Stack.
Peek With Peek, you take the top element and copy it to the return value, but it is not removed.
Count To avoid exceptions with an empty stack, use the Count property and test it against zero.
VB.NET program that uses Stack
Module Module1 Sub Main() Dim stack As Stack(Of Integer) = New Stack(Of Integer) stack.Push(10) stack.Push(100) stack.Push(1000) ' Display stack elements. For Each value As Integer In stack Console.WriteLine(value) Next End Sub End Module
1000 100 10
Example 3. In this example, we show how to copy an array into a new Stack. Please note that the types of the two collections must match. The array of Strings must be copied to a Stack of Strings.
Array
Next We use the Contains function, which works in much the same way as the List Contains function. It returns True or False.
List
VB.NET program that uses Pop and Peek
Module Module1 Sub Main() Dim stack As Stack(Of Integer) = New Stack(Of Integer) stack.Push(10) stack.Push(100) stack.Push(1000) ' Test Pop. Dim value As Integer = stack.Pop Console.WriteLine("Element popped: {0}", value) ' Test Peek. value = stack.Peek Console.WriteLine("Element peeked: {0}", value) End Sub End Module
Element popped: 1000 Element peeked: 100
Summary. The Stack collection can be used to implement certain parsers that track nesting levels, such as HTML parsers. As each nested element is encountered, a new element is added to the Stack.
Note Stacks are useful in any system where the most recently added element is the most urgent.
Thus The VB.NET Stack type is used to implement a variety of important algorithms.
VB.NET program that uses Stack constructor and Contains
Module Module1 Sub Main() Dim array(2) As String array(0) = "dot" array(1) = "net" array(2) = "perls" ' Copy array to a new stack. Dim stack As Stack(Of String) = New Stack(Of String)(array) ' Use Contains. Console.WriteLine(stack.Contains("net")) Console.WriteLine(stack.Contains("not")) End Sub End Module
True False
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