Array.Resize<T>(T[], Int32) Method
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Changes the number of elements of a one-dimensional array to the specified new size.
public:
generic <typename T>
static void Resize(cli::array <T> ^ % array, int newSize);
public static void Resize<T> (ref T[] array, int newSize);
public static void Resize<T> (ref T[]? array, int newSize);
static member Resize : T[] * int -> unit
Public Shared Sub Resize(Of T) (ByRef array As T(), newSize As Integer)
- T
The type of the elements of the array.
- array
- T[]
The one-dimensional, zero-based array to resize, or null
to create a new array with the specified size.
- newSize
- Int32
The size of the new array.
newSize
is less than zero.
The following example shows how resizing affects the array.
using namespace System;
static void PrintIndexAndValues(array<String^>^myArr)
{
for(int i = 0; i < myArr->Length; i++)
{
Console::WriteLine(L" [{0}] : {1}", i, myArr[i]);
}
Console::WriteLine();
}
int main()
{
// Create and initialize a new string array.
array<String^>^myArr = {L"The", L"quick", L"brown", L"fox",
L"jumps", L"over", L"the", L"lazy", L"dog"};
// Display the values of the array.
Console::WriteLine(
L"The string array initially contains the following values:");
PrintIndexAndValues(myArr);
// Resize the array to a bigger size (five elements larger).
Array::Resize(myArr, myArr->Length + 5);
// Display the values of the array.
Console::WriteLine(L"After resizing to a larger size, ");
Console::WriteLine(L"the string array contains the following values:");
PrintIndexAndValues(myArr);
// Resize the array to a smaller size (four elements).
Array::Resize(myArr, 4);
// Display the values of the array.
Console::WriteLine(L"After resizing to a smaller size, ");
Console::WriteLine(L"the string array contains the following values:");
PrintIndexAndValues(myArr);
return 1;
}
/*
This code produces the following output.
The string array initially contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
After resizing to a larger size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
[9] :
[10] :
[11] :
[12] :
[13] :
After resizing to a smaller size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
*/
using System;
public class SamplesArray
{
public static void Main() {
// Create and initialize a new string array.
String[] myArr = {"The", "quick", "brown", "fox", "jumps",
"over", "the", "lazy", "dog"};
// Display the values of the array.
Console.WriteLine(
"The string array initially contains the following values:");
PrintIndexAndValues(myArr);
// Resize the array to a bigger size (five elements larger).
Array.Resize(ref myArr, myArr.Length + 5);
// Display the values of the array.
Console.WriteLine("After resizing to a larger size, ");
Console.WriteLine("the string array contains the following values:");
PrintIndexAndValues(myArr);
// Resize the array to a smaller size (four elements).
Array.Resize(ref myArr, 4);
// Display the values of the array.
Console.WriteLine("After resizing to a smaller size, ");
Console.WriteLine("the string array contains the following values:");
PrintIndexAndValues(myArr);
}
public static void PrintIndexAndValues(String[] myArr) {
for(int i = 0; i < myArr.Length; i++)
{
Console.WriteLine(" [{0}] : {1}", i, myArr[i]);
}
Console.WriteLine();
}
}
/*
This code produces the following output.
The string array initially contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
After resizing to a larger size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
[9] :
[10] :
[11] :
[12] :
[13] :
After resizing to a smaller size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
*/
open System
let printIndexAndValues (myArr: string []) =
for i = 0 to myArr.Length - 1 do
printfn $" [{i}] : {myArr[i]}"
printfn ""
// Create and initialize a new string array.
let mutable myArr =
[| "The"; "quick"; "brown"; "fox"; "jumps"
"over"; "the"; "lazy"; "dog" |]
// Display the values of the array.
printfn "The string array initially contains the following values:"
printIndexAndValues myArr
// Resize the array to a bigger size (five elements larger).
Array.Resize(&myArr, myArr.Length + 5)
// Display the values of the array.
printfn "After resizing to a larger size, "
printfn "the string array contains the following values:"
printIndexAndValues myArr
// Resize the array to a smaller size (four elements).
Array.Resize(&myArr, 4)
// Display the values of the array.
printfn "After resizing to a smaller size, "
printfn "the string array contains the following values:"
printIndexAndValues myArr
(*
This code produces the following output.
The string array initially contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
After resizing to a larger size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
[9] :
[10] :
[11] :
[12] :
[13] :
After resizing to a smaller size,
the string array contains the following values:
[0] : The
[1] : quick
[2] : brown
[3] : fox
*)
Public Class SamplesArray
Public Shared Sub Main()
' Create and initialize a new string array.
Dim myArr As String() = {"The", "quick", "brown", "fox", _
"jumps", "over", "the", "lazy", "dog"}
' Display the values of the array.
Console.WriteLine( _
"The string array initially contains the following values:")
PrintIndexAndValues(myArr)
' Resize the array to a bigger size (five elements larger).
Array.Resize(myArr, myArr.Length + 5)
' Display the values of the array.
Console.WriteLine("After resizing to a larger size, ")
Console.WriteLine("the string array contains the following values:")
PrintIndexAndValues(myArr)
' Resize the array to a smaller size (four elements).
Array.Resize(myArr, 4)
' Display the values of the array.
Console.WriteLine("After resizing to a smaller size, ")
Console.WriteLine("the string array contains the following values:")
PrintIndexAndValues(myArr)
End Sub
Public Shared Sub PrintIndexAndValues(myArr() As String)
Dim i As Integer
For i = 0 To myArr.Length - 1
Console.WriteLine(" [{0}] : {1}", i, myArr(i))
Next i
Console.WriteLine()
End Sub
End Class
'This code produces the following output.
'
'The string array initially contains the following values:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
' [4] : jumps
' [5] : over
' [6] : the
' [7] : lazy
' [8] : dog
'
'After resizing to a larger size,
'the string array contains the following values:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
' [4] : jumps
' [5] : over
' [6] : the
' [7] : lazy
' [8] : dog
' [9] :
' [10] :
' [11] :
' [12] :
' [13] :
'
'After resizing to a smaller size,
'the string array contains the following values:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
This method allocates a new array with the specified size, copies elements from the old array to the new one, and then replaces the old array with the new one. array
must be a one-dimensional array.
If array
is null
, this method creates a new array with the specified size.
If newSize
is greater than the Length of the old array, a new array is allocated and all the elements are copied from the old array to the new one. If newSize
is less than the Length of the old array, a new array is allocated and elements are copied from the old array to the new one until the new one is filled; the rest of the elements in the old array are ignored. If newSize
is equal to the Length of the old array, this method does nothing.
This method is an O(n
) operation, where n
is newSize
.
The Resize method resizes a one-dimensional array only. The Array class does not include a method for resizing multi-dimensional arrays. To do this, you must either provide your own code or call a special-purpose method in a third-party library. The following code illustrates one possible implementation for a method that resizes an array of n dimensions.
using System;
public class Example
{
public static void Main()
{
int[,] arr = new int[10,2];
for (int n1 = 0; n1 <= arr.GetUpperBound(0); n1++) {
arr[n1, 0] = n1;
arr[n1, 1] = n1 * 2;
}
// Make a 2-D array larger in the first dimension.
arr = (int[,]) ResizeArray(arr, new int[] { 12, 2} );
for (int ctr = 0; ctr <= arr.GetUpperBound(0); ctr++)
Console.WriteLine("{0}: {1}, {2}", ctr, arr[ctr, 0], arr[ctr, 1]);
Console.WriteLine();
// Make a 2-D array smaller in the first dimension.
arr = (int[,]) ResizeArray(arr, new int[] { 2, 2} );
for (int ctr = 0; ctr <= arr.GetUpperBound(0); ctr++)
Console.WriteLine("{0}: {1}, {2}", ctr, arr[ctr, 0], arr[ctr, 1]);
}
private static Array ResizeArray(Array arr, int[] newSizes)
{
if (newSizes.Length != arr.Rank)
throw new ArgumentException("arr must have the same number of dimensions " +
"as there are elements in newSizes", "newSizes");
var temp = Array.CreateInstance(arr.GetType().GetElementType(), newSizes);
int length = arr.Length <= temp.Length ? arr.Length : temp.Length;
Array.ConstrainedCopy(arr, 0, temp, 0, length);
return temp;
}
}
// The example displays the following output:
// 0: 0, 0
// 1: 1, 2
// 2: 2, 4
// 3: 3, 6
// 4: 4, 8
// 5: 5, 10
// 6: 6, 12
// 7: 7, 14
// 8: 8, 16
// 9: 9, 18
// 10: 0, 0
// 11: 0, 0
//
// 0: 0, 0
// 1: 1, 2
open System
let resizeArray (arr: Array) (newSizes: int []) =
if newSizes.Length <> arr.Rank then
invalidArg "newSizes" "arr must have the same number of dimensions as there are elements in newSizes"
let temp = Array.CreateInstance(arr.GetType().GetElementType(), newSizes)
let length = min arr.Length temp.Length
Array.ConstrainedCopy(arr, 0, temp, 0, length)
temp
[<EntryPoint>]
let main _ =
let arr = Array2D.init 10 2 (fun x y -> if y = 0 then x else x * 2)
// Make a 2-D array larger in the first dimension.
let arr = resizeArray arr [| 12; 2 |]
for i = 0 to arr.GetUpperBound 0 do
printfn $"{i}: {arr.GetValue(i, 0)}, {arr.GetValue(i, 1)}"
printfn ""
// Make a 2-D array smaller in the first dimension.
let arr = resizeArray arr [| 2; 2|]
for i = 0 to arr.GetUpperBound 0 do
printfn $"{i}: {arr.GetValue(i, 0)}, {arr.GetValue(i, 1)}"
0
// The example displays the following output:
// 0: 0, 0
// 1: 1, 2
// 2: 2, 4
// 3: 3, 6
// 4: 4, 8
// 5: 5, 10
// 6: 6, 12
// 7: 7, 14
// 8: 8, 16
// 9: 9, 18
// 10: 0, 0
// 11: 0, 0
//
// 0: 0, 0
// 1: 1, 2
Module Example
Public Sub Main()
Dim arr(9, 1) As Integer
For n1 As Integer = 0 To arr.GetUpperBound(0)
arr(n1, 0) = n1
arr(n1, 1) = n1 * 2
Next
' Make a 2-D array larger in the first dimension.
arr = CType(ResizeArray(arr, { 12, 2} ), Integer(,))
For ctr = 0 To arr.GetUpperBound(0)
Console.WriteLine("{0}: {1}, {2}", ctr, arr(ctr, 0), arr(ctr, 1))
Next
Console.WriteLine()
' Make a 2-D array smaller in the first dimension.
arr = CType(ResizeArray(arr, { 2, 2} ), Integer(,))
For ctr = 0 To arr.GetUpperBound(0)
Console.WriteLine("{0}: {1}, {2}", ctr, arr(ctr, 0), arr(ctr, 1))
Next
End Sub
Private Function ResizeArray(arr As Array, newSizes() As Integer) As Array
If newSizes.Length <> arr.Rank Then
Throw New ArgumentException("arr must have the same number of dimensions " +
"as there are elements in newSizes", "newSizes")
End If
Dim temp As Array = Array.CreateInstance(arr.GetType().GetElementType(), newSizes)
Dim length As Integer = If(arr.Length <= temp.Length, arr.Length, temp.Length )
Array.ConstrainedCopy(arr, 0, temp, 0, length)
Return temp
End Function
End Module
' The example displays the following output:
' 0: 0, 0
' 1: 1, 2
' 2: 2, 4
' 3: 3, 6
' 4: 4, 8
' 5: 5, 10
' 6: 6, 12
' 7: 7, 14
' 8: 8, 16
' 9: 9, 18
' 10: 0, 0
' 11: 0, 0
'
' 0: 0, 0
' 1: 1, 2
產品 | 版本 |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
UWP | 10.0 |