# Array.Length プロパティ

## 定義

Array のすべての次元内の要素の総数を取得します。Gets the total number of elements in all the dimensions of the Array.

public:
property int Length { int get(); };
public int Length { get; }
member this.Length : int
Public ReadOnly Property Length As Integer

#### プロパティ値

Int32

Array のすべての次元内の要素の総数。配列内に要素がない場合はゼロ。The total number of elements in all the dimensions of the Array; zero if there are no elements in the array.

## 例

using System;

public class Example
{
public static void Main()
{
// Declare a single-dimensional string array
String[] array1d = { "zero", "one", "two", "three" };
ShowArrayInfo(array1d);

// Declare a two-dimensional string array
String[,] array2d = { { "zero", "0" }, { "one", "1" },
{ "two", "2" }, { "three", "3"},
{ "four", "4" }, { "five", "5" } };
ShowArrayInfo(array2d);

// Declare a three-dimensional integer array
int[, ,] array3d = new int[,,] { { { 1, 2, 3 }, { 4, 5, 6 } },
{ { 7, 8, 9 }, { 10, 11, 12 } } };
ShowArrayInfo(array3d);
}

private static void ShowArrayInfo(Array arr)
{
Console.WriteLine("Length of Array:      {0,3}", arr.Length);
Console.WriteLine("Number of Dimensions: {0,3}", arr.Rank);
// For multidimensional arrays, show number of elements in each dimension.
if (arr.Rank > 1) {
for (int dimension = 1; dimension <= arr.Rank; dimension++)
Console.WriteLine("   Dimension {0}: {1,3}", dimension,
arr.GetUpperBound(dimension - 1) + 1);
}
Console.WriteLine();
}
}
// The example displays the following output:
//       Length of Array:        4
//       Number of Dimensions:   1
//
//       Length of Array:       12
//       Number of Dimensions:   2
//          Dimension 1:   6
//          Dimension 2:   2
//
//       Length of Array:       12
//       Number of Dimensions:   3
//          Dimension 1:   2
//          Dimension 2:   2
//          Dimension 3:   3
Module Example
Public Sub Main()
' Declare a single-dimensional string array
Dim array1d() As String = {"zero", "one", "two", "three"}
ShowArrayInfo(array1d)

' Declare a two-dimensional string array
Dim array2d(,) As String = {{"zero", "0"}, {"one", "1"},
{"two", "2"}, {"three", "3"},
{"four", "4"}, {"five", "5"}}
ShowArrayInfo(array2d)

' Declare a three-dimensional integer array
Dim array3d(,,) As Integer = New Integer(,,) {{{1, 2, 3}, {4, 5, 6}},
{{7, 8, 9}, {10, 11, 12}}}
ShowArrayInfo(array3d)

End Sub

Private Sub ShowArrayInfo(arr As Array)
Console.WriteLine("Length of Array:      {0,3}", arr.Length)
Console.WriteLine("Number of Dimensions: {0,3}", arr.Rank)
' For multidimensional arrays, show number of elements in each dimension.
If arr.Rank > 1 Then
For dimension As Integer = 1 To arr.Rank
Console.WriteLine("   Dimension {0}: {1,3}", dimension,
arr.GetUpperBound(dimension - 1) + 1)
Next
End If
Console.WriteLine()
End Sub
End Module
' The example displays the following output:
'       Length of Array:        4
'       Number of Dimensions:   1
'
'       Length of Array:       12
'       Number of Dimensions:   2
'          Dimension 1:   6
'          Dimension 2:   2
'
'       Length of Array:       12
'       Number of Dimensions:   3
'          Dimension 1:   2
'          Dimension 2:   2
'          Dimension 3:   3

## 注釈

このプロパティ値を取得することは、O(1) 操作になります。Retrieving the value of this property is an O(1) operation.