arrays - 如何在 Visual Basic 中从数组中选择一个随机元素

Question

我创建了一个整数数组，并想从中选择一个随机元素。我怎么做？

Answer 1

YourArray(New Random().Next(0,YourArray.Length-1))

或者为了更清楚而分开：

Dim Rand as New Random()
Dim Index as Integer = Rand.Next(0, YourArray.Length - 1)

Dim SelectedValue = YourArray(Index)

Answer 2

0在 到 的范围内生成一个随机整数Len-1，其中Len是数组的长度。要生成随机整数，请使用Random该类的实例。

DIM rand As New Random
DIM idx as rand.Next(0, Len)
REM Now you can pick an element idx from the array
REM to get a random element.
DIM res as myArray(index)

Answer 3

Rnd可以得到[0,1)，然后再多倍你的arraylength，你可以得到[0,YourArrayLength)之间的数字

Randomize
Int(array.length* Rnd)

Answer 4

只想说接受的答案是不正确的。

这是正确的

Dim Rand as New Random()
Dim Index as Integer = Rand.Next(0, YourArray.Length)

Dim SelectedValue = YourArray(Index)

为什么？

因为最大值是排他的。因此，如果您不想在 3 个元素中进行选择，例如，最大值应该是 3，而不是 2。

    '
    ' Summary:
    '     Returns a non-negative random integer.
    '
    ' Returns:
    '     A 32-bit signed integer that is greater than or equal to 0 and less than System.Int32.MaxValue.
    Public Overridable Function [Next]() As Integer
    '
    ' Summary:
    '     Returns a random integer that is within a specified range.
    '
    ' Parameters:
    '   minValue:
    '     The inclusive lower bound of the random number returned.
    '
    '   maxValue:
    '     The **exclusive** upper bound of the random number returned. maxValue must be greater
    '     than or equal to minValue.
    '
    ' Returns:
    '     A 32-bit signed integer greater than or equal to minValue and **less than** maxValue;
    '     that is, the range of return values includes minValue but not maxValue. If minValue
    '     equals maxValue, minValue is returned.
    '
    ' Exceptions:
    '   T:System.ArgumentOutOfRangeException:
    '     minValue is greater than maxValue.

我也试过。我尝试从 3 个元素中选择一个，并注意到只有前 2 个元素被选中。永远不会选择第三个元素