Question

我想在vb.net中生成一个6个随机数的随机数，这个数字应该是数字，有时也是alphanumerice.Like ist 4或5个数字应该是数字，接下来应该是alphnumeric.I分开创建两个数字。像这样

Public Function rand() As String
        'Number
        Dim rng As Random = New Random
        Dim number As Integer = rng.Next(1, 1000000)
        Dim digits As String = number.ToString("000000")
        'Alphnumeric
        Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
        Dim r As New Random
        Dim sb As New StringBuilder
        For i As Integer = 1 To 5
            Dim idx As Integer = r.Next(0, 35)
            sb.Append(s.Substring(idx, 1))
        Next
    End Function

现在任何人都有这个想法，在这个函数中，我可以返回数字和一些字符串，或者可以是一个创建数字和字符串的单个实例。

Answer 1

要解决的第一个问题是随机数生成器。您应该只使用一个实例，而不是多个实例，如果在短时间内调用，则会返回相同的序列。然后就是很难说你的要求中有什么“东西”意味着什么，但假设你有70％的粗糙数字和30％的数字和字符串组合，那么你可以调用随机生成器来决定一系列只有数字或混合数字。基于从适当的字符串随机选择序列构建的输出

' A global unique random generator'
Dim rng As Random = New Random
Sub Main
    Console.WriteLine(rand())
    Console.WriteLine(rand())
    Console.WriteLine(rand())
    Console.WriteLine(rand())
End Sub

Public Function rand() As String

    Dim sb As New StringBuilder

    ' Selection of pure numbers sequence or mixed one
    Dim pureNumbers = rng.Next(1,11)
    if pureNumbers < 7 then
        ' Generate a sequence of only digits
        Dim number As Integer = rng.Next(1, 1000000)
        Dim digits As String = number.ToString("000000")
        For i As Integer = 1 To 6
            Dim idx As Integer = rng.Next(0, digits.Length)
            sb.Append(digits.Substring(idx, 1))
        Next
    else
        ' Generate a sequence of digits and letters 
        Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
        For i As Integer = 1 To 6
            Dim idx As Integer = rng.Next(0, 36)
            sb.Append(s.Substring(idx, 1))
        Next
    End if 
    return sb.ToString()
End Function

vb.net生成随机数和字符串

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