vb 编程题、

1、求1-1000内的素数（过程要编写为函数）2、随机产生4位数，然后排序、将结果输出到一个文件。　　　　　　　　　　大家帮个忙吧、小弟不大懂这个阿

答案：经常遇到类似的题目，可以参考此程序！
　　VB 2008 调试通过！

Public Class Form1
    Dim prime(100) As Integer
    Dim CurrentIndex As Integer
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        TextBox1.ScrollBars = ScrollBars.Vertical
        CurrentIndex = 1
        prime(CurrentIndex) = 2
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer
        Dim sum As Integer
        For i = 3 To 200 Step 2                                      '显然，单数才有可能是素数
            If IsPrime(i) Then
                CurrentIndex = CurrentIndex + 1
                prime(CurrentIndex) = i
            End If
        Next
        sum = 0
        For i = 1 To CurrentIndex                                               '输出到 textbox 框中，一行一个数，并 累计 求和，结果也 输出 在 此框！
            TextBox1.Text = TextBox1.Text & i & ", " & prime(i) & vbCrLf
            sum = sum + prime(i)
        Next
        TextBox1.Text = TextBox1.Text & vbCrLf & "sum, " & sum & vbCrLf

    End Sub

    Private Function IsPrime(ByVal number As Integer) As Boolean   '自定义函数，判断是否为素数
        Dim i As Integer
        IsPrime = True
        For i = 1 To CurrentIndex
            If number Mod prime(i) Then                                                '用这个数除以自知 的 素数，能整除的显然不是 素数
            Else
                IsPrime = False
                Exit Function
            End If
        Next
    End Function
End Class

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