CODEWITHSUNDEEP
arraysvisual-studio-2008vbarandom
ShuklaSannidhya
ShuklaSannidhya

Reputation: 8976

How to choose a random element from an array in Visual Basic

I have created an array of Integer and want to choose a random element from it. How do I do that?

Upvotes: 1

Views: 33303

Answers (4)

user4951
user4951

Reputation: 33050

Just want to say that the accepted answer is incorrect.

This is the correct one

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

Dim SelectedValue = YourArray(Index)

Why?

Because the maximum value is exclusive. So if you won't to pick among 3 elements, for example, the maximum value should be 3, not 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.

I also tried. I tried to select one out of 3 elements and notice that only the first 2 elements get chosen. The third element is never chosen enter image description here

Upvotes: 0

beezir
beezir

Reputation: 460

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

Or separated out for more clarity:

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

Dim SelectedValue = YourArray(Index)

Upvotes: 7

Tony Stark
Tony Stark

Reputation: 172

Rnd can get [0,1),then mutiple Your arraylength, you can get number between [0,YourArrayLength)

Randomize
Int(array.length* Rnd)

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726479

Make a random integer number in the range from 0 to Len-1, where Len is the length of your array. To make a random integer, use an instance of the Random class.

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)

Upvotes: 1

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