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VB学习第十二周输出显示n以内的素数，
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'(3)输出显示n以内的素数1
Public Class Form1
Private Sub TextBox1_KeyPress(ByVal sender As Object,ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
Dim i,n,m As Integer,Tag As Boolean
Dim x() = {0}
If Asc(e.KeyChar) = 13 Then
If Not IsNumeric(TextBox1.Text) Then
TextBox1.Text = ""
TextBox1.Focus()
Else
m = Val(TextBox1.Text)
For n = 3 To m
Tag = True
For i = 2 To n - 1
If (n Mod i) = 0 Then Tag = False
Next
If Tag Then
If x(0) = 0 Then
x(0) = n
Else
ReDim Preserve x(UBound(x) + 1)
x(UBound(x)) = n
End If
End If
Next
End If
Label3.Text = ""
If x(0) = 0 Then
Label3.Text = Str(m) & "以内没有素数"
Else
For i = 0 To UBound(x)
Label3.Text &= Space(5 - Len(Str(x(i)))) & Str(x(i))
If ((i + 1) Mod 5 = 0) Then Label3.Text &= vbCrLf
Next
End If
End If
End Sub
End Class
'(4)输出显示n以内的素数2
Public Class Form1
Private Sub TextBox1_KeyPress(ByVal sender As Object,Tag As Boolean
Dim x() = {0}
If Asc(e.KeyChar) = 13 Then
If Not IsNumeric(TextBox1.Text) Then
TextBox1.Text = ""
TextBox1.Focus()
Else
m = Val(TextBox1.Text)
For n = 3 To m
Tag = True
For i = 2 To n - 1
If (n Mod i) = 0 Then Tag = False
Next
If Tag Then
If x(0) = 0 Then
x(0) = n
Else
ReDim Preserve x(UBound(x) + 1)
x(UBound(x)) = n
End If
End If
Next
End If
ListBox1.Items.Clear()
For i = 0 To UBound(x)
ListBox1.Items.Add(x(i))
Next
End If
End Sub
End Class
