Vb.net随机数生成器多次生成相同的数字

我有这个程序从文件中生成名字和姓氏。当我运行该程序时，我在三个文本框中输入信息。前两个是工资低和高（salary1.text，salary2.text），最后一个是我想要的“份数”（copies.text）。当我在文本中输入诸如10之类的数字时它会输出一些相同的名称。

名字文件大约有 100 条记录 姓氏文件大约有1000条记录

为什么会生成相同的名称

如果我执行 1000 份副本之类的操作，问题会更严重。它会输出相同的内容 8 次，然后再执行不同的操作 8 次

Public Class Form1

    Dim sex As String

Function randomfirstname()
    Dim infile As IO.StreamReader
    Dim infile1 As IO.StreamReader
    Dim male() As String
    Dim female() As String
    Dim name As String
    Dim n As Integer = 0
    Dim fun As New System.Random
    Dim maleorfemale As New Random()
    Dim RandomNumber As Integer
    Dim index As Integer
    RandomNumber = maleorfemale.Next(0, 55984)
    infile = IO.File.OpenText("boysnames.txt")
    infile1 = IO.File.OpenText("girlsnames.txt")

    If RandomNumber Mod 2 = 0 Then
        While infile.Peek <> -1
            ReDim Preserve male(n)
            male(n) = infile.ReadLine
            n = n + 1
        End While
        n = n - 1
        index = fun.Next(0, n)
        name = male(index)
        sex = "M"
        n = 0
        Return name


    Else
        While infile1.Peek <> -1
            ReDim Preserve female(n)
            female(n) = infile1.ReadLine
            n = n + 1
        End While
        n = n - 1
        index = fun.Next(0, n)
        name = female(index)
        sex = "F"
        Return name
        n = 0
    End If
End Function
Function randomlastname()
    Dim infile2 As IO.StreamReader
    Dim lname() As String
    Dim lastname As String
    Dim n As Integer = 0
    Dim index As Integer
    Dim fun As New System.Random
    infile2 = IO.File.OpenText("lastname.txt")
    While infile2.Peek <> -1
        ReDim Preserve lname(n)
        lname(n) = infile2.ReadLine
        n = n + 1
    End While
    n = n - 1
    index = fun.Next(0, n)
    lastname = lname(index)
    Return lastname
End Function
Function salary()
    Dim salary01 As Double
    Dim salary02 As Double
    Dim salary03 As Double
    salary01 = CDbl(salary1.Text)
    salary02 = CDbl(salary2.Text)
    Dim sal As New System.Random


    salary03 = System.Math.Round(sal.NextDouble() * (salary02 - salary01) + salary01, 2)
    Return salary03
End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    'ListBox1.Items.Add(randomfirstname() & vbTab & randomlastname() & vbTab & sex & vbTab & salary())
    Dim outfile As New System.IO.StreamWriter("C:\Users\Johnathon\Desktop\486assign1.txt")
    Dim i As Integer = 0
    outfile.Write("Firstname" & vbTab & "LastName" & vbTab & "Sex" & vbTab & "Salary" & vbCrLf)
    outfile.Write("-----------------------------------------------------------------------------" & vbCrLf)

    For i = 1 To CInt(copies.Text)
        outfile.Write(randomfirstname() & vbTab & randomlastname() & vbTab & sex & vbTab & salary() & vbCrLf)
        ListBox1.Items.Add(randomfirstname() & vbTab & randomlastname() & vbTab & sex & vbTab & salary())
    Next
    outfile.Close()

End Sub
End Class

包含 10 条记录的示例输出

Firstname   LastName    Sex Salary
-----------------------------------------------------------------------------
Carson  Gillespie   M   8.46    
Carson  Gillespie   M   8.46
Carson  Gillespie   M   8.46
Samantha    Daniels F   5.84
Samantha    Daniels F   5.84
Samantha    Daniels F   5.84
Natalia Guthrie F   9.26
Natalia Guthrie F   9.26
Natalia Guthrie F   9.26
Natalia Guthrie F   6.64

您正在使用的新实例System.Random每次。Random是在当前时间播种的。

使用与时间相关的默认种子值初始化 Random 类的新实例

参考

由于您正在快速连续地创建新实例，因此它们会获得相同的种子。

相反，您应该使用相同的实例Random，可能通过将其设为字段并初始化为字段初始值设定项或构造函数。例如：

Public Class Form1
    Private _random As New System.Random()

    'Use _random in other methods.
End Class