'(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
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