Stack<T>.CopyTo(T[], Int32) Method
Definition
Important
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public: void CopyTo(cli::array <T> ^ array, int arrayIndex);public void CopyTo(T[] array, int arrayIndex);member this.CopyTo : 'T[] * int -> unitPublic Sub CopyTo (array As T(), arrayIndex As Integer)Parameters
- array
- T[]
The one-dimensional Array that is the destination of the elements copied from Stack<T>. The Array must have zero-based indexing.
- arrayIndex
- Int32
The zero-based index in array at which copying begins.
Exceptions
array is null.
arrayIndex is less than zero.
The number of elements in the source Stack<T> is greater than the available space from arrayIndex to the end of the destination array.
Examples
The following code example demonstrates several methods of the Stack<T> generic class, including the CopyTo method.
The code example creates a stack of strings with default capacity and uses the Push method to push five strings onto the stack. The elements of the stack are enumerated, which does not change the state of the stack. The Pop method is used to pop the first string off the stack. The Peek method is used to look at the next item on the stack, and then the Pop method is used to pop it off.
The ToArray method is used to create an array and copy the stack elements to it, then the array is passed to the Stack<T> constructor that takes IEnumerable<T>, creating a copy of the stack with the order of the elements reversed. The elements of the copy are displayed.
An array twice the size of the stack is created, and the CopyTo method is used to copy the array elements beginning at the middle of the array. The Stack<T> constructor is used again to create a copy of the stack with the order of elements reversed; thus, the three null elements are at the end.
The Contains method is used to show that the string "four" is in the first copy of the stack, after which the Clear method clears the copy and the Count property shows that the stack is empty.
using System; using System.Collections.Generic; class Example { public static void Main() { Stack<string> numbers = new Stack<string>(); numbers.Push("one"); numbers.Push("two"); numbers.Push("three"); numbers.Push("four"); numbers.Push("five"); // A stack can be enumerated without disturbing its contents. foreach( string number in numbers ) { Console.WriteLine(number); } Console.WriteLine("\nPopping '{0}'", numbers.Pop()); Console.WriteLine("Peek at next item to destack: {0}", numbers.Peek()); Console.WriteLine("Popping '{0}'", numbers.Pop()); // Create a copy of the stack, using the ToArray method and the // constructor that accepts an IEnumerable<T>. Stack<string> stack2 = new Stack<string>(numbers.ToArray()); Console.WriteLine("\nContents of the first copy:"); foreach( string number in stack2 ) { Console.WriteLine(number); } // Create an array twice the size of the stack and copy the // elements of the stack, starting at the middle of the // array. string[] array2 = new string[numbers.Count * 2]; numbers.CopyTo(array2, numbers.Count); // Create a second stack, using the constructor that accepts an // IEnumerable(Of T). Stack<string> stack3 = new Stack<string>(array2); Console.WriteLine("\nContents of the second copy, with duplicates and nulls:"); foreach( string number in stack3 ) { Console.WriteLine(number); } Console.WriteLine("\nstack2.Contains(\"four\") = {0}", stack2.Contains("four")); Console.WriteLine("\nstack2.Clear()"); stack2.Clear(); Console.WriteLine("\nstack2.Count = {0}", stack2.Count); } } /* This code example produces the following output: five four three two one Popping 'five' Peek at next item to destack: four Popping 'four' Contents of the first copy: one two three Contents of the second copy, with duplicates and nulls: one two three stack2.Contains("four") = False stack2.Clear() stack2.Count = 0 */ open System open System.Collections.Generic let numbers = Stack() numbers.Push "one" numbers.Push "two" numbers.Push "three" numbers.Push "four" numbers.Push "five" // A stack can be enumerated without disturbing its contents. for number in numbers do printfn $"{number}" printfn $"\nPopping '{numbers.Pop()}'" printfn $"Peek at next item to destack: {numbers.Peek()}" numbers.Peek() |> ignore printfn $"Popping '{numbers.Pop()}'" // Create a copy of the stack, using the ToArray method and the // constructor that accepts an IEnumerable<T>. let stack2 = numbers.ToArray() |> Stack printfn "\nContents of the first copy:" for number in stack2 do printfn $"{number}" // Create an array twice the size of the stack and copy the // elements of the stack, starting at the middle of the // array. let array2 = numbers.Count * 2 |> Array.zeroCreate numbers.CopyTo(array2, numbers.Count) // Create a second stack, using the constructor that accepts an // IEnumerable(Of T). let stack3 = Stack array2 printfn "\nContents of the second copy, with duplicates and nulls:" for number in stack3 do printfn $"{number}" printfn $""" stack2.Contains "four" = {stack2.Contains "four"}""" printfn "\nstack2.Clear()" stack2.Clear() printfn $"\nstack2.Count = {stack2.Count}" // This code example produces the following output: // five // four // three // two // one // // Popping 'five' // Peek at next item to destack: four // Popping 'four' // // Contents of the first copy: // one // two // three // // Contents of the second copy, with duplicates and nulls: // one // two // three // // stack2.Contains("four") = False // // stack2.Clear() // // stack2.Count = 0 Imports System.Collections.Generic Module Example Sub Main Dim numbers As New Stack(Of String) numbers.Push("one") numbers.Push("two") numbers.Push("three") numbers.Push("four") numbers.Push("five") ' A stack can be enumerated without disturbing its contents. For Each number As String In numbers Console.WriteLine(number) Next Console.WriteLine(vbLf & "Popping '{0}'", numbers.Pop()) Console.WriteLine("Peek at next item to pop: {0}", _ numbers.Peek()) Console.WriteLine("Popping '{0}'", numbers.Pop()) ' Create another stack, using the ToArray method and the ' constructor that accepts an IEnumerable(Of T). Note that ' the order of items on the new stack is reversed. Dim stack2 As New Stack(Of String)(numbers.ToArray()) Console.WriteLine(vbLf & "Contents of the first copy:") For Each number As String In stack2 Console.WriteLine(number) Next ' Create an array twice the size of the stack, compensating ' for the fact that Visual Basic allocates an extra array ' element. Copy the elements of the stack, starting at the ' middle of the array. Dim array2((numbers.Count * 2) - 1) As String numbers.CopyTo(array2, numbers.Count) ' Create a second stack, using the constructor that accepts an ' IEnumerable(Of T). The elements are reversed, with the null ' elements appearing at the end of the stack when enumerated. Dim stack3 As New Stack(Of String)(array2) Console.WriteLine(vbLf & _ "Contents of the second copy, with duplicates and nulls:") For Each number As String In stack3 Console.WriteLine(number) Next Console.WriteLine(vbLf & "stack2.Contains(""four"") = {0}", _ stack2.Contains("four")) Console.WriteLine(vbLf & "stack2.Clear()") stack2.Clear() Console.WriteLine(vbLf & "stack2.Count = {0}", _ stack2.Count) End Sub End Module ' This code example produces the following output: ' 'five 'four 'three 'two 'one ' 'Popping 'five' 'Peek at next item to pop: four 'Popping 'four' ' 'Contents of the first copy: 'one 'two 'three ' 'Contents of the second copy, with duplicates and nulls: 'one 'two 'three ' ' ' ' 'stack2.Contains("four") = False ' 'stack2.Clear() ' 'stack2.Count = 0 Remarks
The elements are copied onto the array in last-in-first-out (LIFO) order, similar to the order of the elements returned by a succession of calls to Pop.
This method is an O(n) operation, where n is Count.
