vb.net求导数 vb求导函数

急急急！！十万火急！！求VB.NET高手！！！

描述不够清楚，也没有图。你的界面是什么界面，是窗体还是其他的什么。

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如果是窗体，他会让你导入图片，作为资源存在工程里面。

如果不是，你先要把背景图片放到资源里再调用。

又或者你的界面图片被别的控件挡住了，你需要将别的控件的backcolor属性改为transparent。

总之你想问什么问题，你得描述清楚。

请问这道VB.net怎么编程

1、作验证，可用正则表达式、vb.net的自带函数（相对简单）

2、可采用排序方式

3、循环加限制条件

4 write

VB.net round问题

这应该是由浮点数的误差所造成的，你把kk设为双精度浮点数，那么结果就是1.34

但是浮点数误差与精度是无关的，双精度也同样存在，继续测试你就会发现有趣的现象：

下面假定s为单精度浮点数变量，d为双精度浮点数变量，则：

s = 1.345 Round(s, 2) = 1.35 （错）

d = 1.345 Round(d, 2) = 1.34 （对）

s = 2.345 Round(s, 2) = 2.35 （错）

d = 2.345 Round(d, 2) = 2.35 （错）

s = 3.345 Round(s, 2) = 3.35 （错）

d = 3.345 Round(d, 2) = 3.34 （对）

s = 4.345 Round(s, 2) = 4.34 （对）

d = 4.345 Round(d, 2) = 4.34 （对）

可以发现这错误的发生是毫无规律的，有时候真能让人发疯！

VB.net过程的调用

Sub过程实现：

Sub FactsSub(ByVal intN As Integer, ByRef result As Long)

Dim i As Integer

Dim lngResult As Long

lngResult = 1

For i = 1 To intN

lngResult *= i

Next

result = lngResult

End Sub

Private Sub btnSub_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSub.Click

Dim i As Integer

Dim sum As Long = 0

Dim result As Long

For i = 1 To 10

FactsSub(i, result)

sum += result

Next

MsgBox("过程实现 1! + 2! + 3! + … + 10! = " sum)

End Sub

Function函数实现:

Function FactsFunction(ByVal intN As Integer) As Long

Dim i As Integer

Dim lngResult As Long

lngResult = 1

For i = 1 To intN

lngResult *= i

Next

Return lngResult

End Function

Private Sub btnFunction_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFunction.Click

Dim i As Integer

Dim sum As Long = 0

For i = 1 To 10

sum += FactsFunction(i)

Next

MsgBox("函数实现 1! + 2! + 3! + … + 10! = " sum)

End Sub

VB.NET中的一个方法

用replace函数

Replace(expression, find, replacewith)

Replace函数语法有如下几部分：

expression 字符串表达式，包含要替换的子字符串。

find 要搜索到的子字符串。

replacewith 用来替换的子字符串。

以你的要求:

str=Replace(A,"A","a")

如果你要做一个学生姓名对应一个学生学号，你输了姓名，学号自动就显示出来了.

最好通过数据库实现.

select studentid from student where studentname=输入姓名

用VB.NET编的计算器程序！

Public Class SimpleCalculator

Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

Public Sub New()

MyBase.New()

'该调用是 Windows 窗体设计器所必需的。

InitializeComponent()

'在 InitializeComponent() 调用之后添加任何初始化

End Sub

'窗体重写处置以清理组件列表。

Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)

If disposing Then

If Not (components Is Nothing) Then

components.Dispose()

End If

End If

MyBase.Dispose(disposing)

End Sub

'Windows 窗体设计器所必需的

Private components As System.ComponentModel.IContainer

'注意：以下过程是 Windows 窗体设计器所必需的

'可以使用 Windows 窗体设计器修改此过程。

'不要使用代码编辑器修改它。

Friend WithEvents Label1 As System.Windows.Forms.Label

Friend WithEvents TextBox1 As System.Windows.Forms.TextBox

Friend WithEvents Button1 As System.Windows.Forms.Button

Friend WithEvents Button2 As System.Windows.Forms.Button

Friend WithEvents Button3 As System.Windows.Forms.Button

Friend WithEvents Button4 As System.Windows.Forms.Button

Friend WithEvents Button5 As System.Windows.Forms.Button

Friend WithEvents Button6 As System.Windows.Forms.Button

Friend WithEvents Button7 As System.Windows.Forms.Button

Friend WithEvents Button8 As System.Windows.Forms.Button

Friend WithEvents Button9 As System.Windows.Forms.Button

Friend WithEvents Button10 As System.Windows.Forms.Button

Friend WithEvents Button11 As System.Windows.Forms.Button

Friend WithEvents Button12 As System.Windows.Forms.Button

Friend WithEvents Button13 As System.Windows.Forms.Button

Friend WithEvents Button14 As System.Windows.Forms.Button

Friend WithEvents Button15 As System.Windows.Forms.Button

Friend WithEvents Button16 As System.Windows.Forms.Button

System.Diagnostics.DebuggerStepThrough() Private Sub InitializeComponent()

Me.Label1 = New System.Windows.Forms.Label

Me.TextBox1 = New System.Windows.Forms.TextBox

Me.Button1 = New System.Windows.Forms.Button

Me.Button2 = New System.Windows.Forms.Button

Me.Button3 = New System.Windows.Forms.Button

Me.Button4 = New System.Windows.Forms.Button

Me.Button5 = New System.Windows.Forms.Button

Me.Button6 = New System.Windows.Forms.Button

Me.Button7 = New System.Windows.Forms.Button

Me.Button8 = New System.Windows.Forms.Button

Me.Button9 = New System.Windows.Forms.Button

Me.Button10 = New System.Windows.Forms.Button

Me.Button11 = New System.Windows.Forms.Button

Me.Button12 = New System.Windows.Forms.Button

Me.Button13 = New System.Windows.Forms.Button

Me.Button14 = New System.Windows.Forms.Button

Me.Button15 = New System.Windows.Forms.Button

Me.Button16 = New System.Windows.Forms.Button

Me.SuspendLayout()

'

'Label1

'

Me.Label1.Location = New System.Drawing.Point(16, 16)

Me.Label1.Name = "Label1"

Me.Label1.Size = New System.Drawing.Size(48, 16)

Me.Label1.TabIndex = 0

Me.Label1.Text = "结果："

'

'TextBox1

'

Me.TextBox1.Location = New System.Drawing.Point(64, 8)

Me.TextBox1.Name = "TextBox1"

Me.TextBox1.Size = New System.Drawing.Size(120, 21)

Me.TextBox1.TabIndex = 1

Me.TextBox1.Text = ""

'

'Button1

'

Me.Button1.Location = New System.Drawing.Point(200, 8)

Me.Button1.Name = "Button1"

Me.Button1.Size = New System.Drawing.Size(56, 24)

Me.Button1.TabIndex = 2

Me.Button1.Text = "清空"

'

'Button2

'

Me.Button2.Location = New System.Drawing.Point(48, 56)

Me.Button2.Name = "Button2"

Me.Button2.Size = New System.Drawing.Size(24, 24)

Me.Button2.TabIndex = 3

Me.Button2.Text = "1"

'

'Button3

'

Me.Button3.Location = New System.Drawing.Point(88, 56)

Me.Button3.Name = "Button3"

Me.Button3.Size = New System.Drawing.Size(24, 24)

Me.Button3.TabIndex = 4

Me.Button3.Text = "2"

'

'Button4

'

Me.Button4.Location = New System.Drawing.Point(136, 56)

Me.Button4.Name = "Button4"

Me.Button4.Size = New System.Drawing.Size(24, 24)

Me.Button4.TabIndex = 5

Me.Button4.Text = "3"

'

'Button5

'

Me.Button5.Location = New System.Drawing.Point(48, 88)

Me.Button5.Name = "Button5"

Me.Button5.Size = New System.Drawing.Size(24, 24)

Me.Button5.TabIndex = 6

Me.Button5.Text = "4"

'

'Button6

'

Me.Button6.Location = New System.Drawing.Point(88, 88)

Me.Button6.Name = "Button6"

Me.Button6.Size = New System.Drawing.Size(24, 24)

Me.Button6.TabIndex = 7

Me.Button6.Text = "5"

'

'Button7

'

Me.Button7.Location = New System.Drawing.Point(136, 88)

Me.Button7.Name = "Button7"

Me.Button7.Size = New System.Drawing.Size(24, 24)

Me.Button7.TabIndex = 8

Me.Button7.Text = "6"

'

'Button8

'

Me.Button8.Location = New System.Drawing.Point(48, 120)

Me.Button8.Name = "Button8"

Me.Button8.Size = New System.Drawing.Size(24, 24)

Me.Button8.TabIndex = 9

Me.Button8.Text = "7"

'

'Button9

'

Me.Button9.Location = New System.Drawing.Point(88, 120)

Me.Button9.Name = "Button9"

Me.Button9.Size = New System.Drawing.Size(24, 24)

Me.Button9.TabIndex = 10

Me.Button9.Text = "8"

'

'Button10

'

Me.Button10.Location = New System.Drawing.Point(136, 120)

Me.Button10.Name = "Button10"

Me.Button10.Size = New System.Drawing.Size(24, 24)

Me.Button10.TabIndex = 11

Me.Button10.Text = "9"

'

'Button11

'

Me.Button11.Location = New System.Drawing.Point(48, 152)

Me.Button11.Name = "Button11"

Me.Button11.Size = New System.Drawing.Size(24, 24)

Me.Button11.TabIndex = 12

Me.Button11.Text = "0"

'

'Button12

'

Me.Button12.Location = New System.Drawing.Point(176, 56)

Me.Button12.Name = "Button12"

Me.Button12.Size = New System.Drawing.Size(24, 24)

Me.Button12.TabIndex = 13

Me.Button12.Text = "+"

'

'Button13

'

Me.Button13.Location = New System.Drawing.Point(176, 88)

Me.Button13.Name = "Button13"

Me.Button13.Size = New System.Drawing.Size(24, 24)

Me.Button13.TabIndex = 14

Me.Button13.Text = "-"

'

'Button14

'

Me.Button14.Location = New System.Drawing.Point(176, 120)

Me.Button14.Name = "Button14"

Me.Button14.Size = New System.Drawing.Size(24, 24)

Me.Button14.TabIndex = 15

Me.Button14.Text = "*"

'

'Button15

'

Me.Button15.Location = New System.Drawing.Point(176, 152)

Me.Button15.Name = "Button15"

Me.Button15.Size = New System.Drawing.Size(24, 24)

Me.Button15.TabIndex = 16

Me.Button15.Text = "/"

'

'Button16

'

Me.Button16.Location = New System.Drawing.Point(88, 152)

Me.Button16.Name = "Button16"

Me.Button16.Size = New System.Drawing.Size(72, 24)

Me.Button16.TabIndex = 17

Me.Button16.Text = "计算"

'

'SimpleCalculator

'

Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)

Me.ClientSize = New System.Drawing.Size(264, 190)

Me.Controls.Add(Me.Button16)

Me.Controls.Add(Me.Button15)

Me.Controls.Add(Me.Button14)

Me.Controls.Add(Me.Button13)

Me.Controls.Add(Me.Button12)

Me.Controls.Add(Me.Button11)

Me.Controls.Add(Me.Button10)

Me.Controls.Add(Me.Button9)

Me.Controls.Add(Me.Button8)

Me.Controls.Add(Me.Button7)

Me.Controls.Add(Me.Button6)

Me.Controls.Add(Me.Button5)

Me.Controls.Add(Me.Button4)

Me.Controls.Add(Me.Button3)

Me.Controls.Add(Me.Button2)

Me.Controls.Add(Me.Button1)

Me.Controls.Add(Me.TextBox1)

Me.Controls.Add(Me.Label1)

Me.Name = "SimpleCalculator"

Me.Text = "简单计算器"

Me.ResumeLayout(False)

End Sub

#End Region

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)

End Sub

Private Sub TextBox1_TabStopChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

Dim btn As Button '按钮类型的变量

btn = sender '把产生该事件的按钮对象赋值给btn

TextBox1.Text = TextBox1.Text + btn.Text '把该按钮的Text属性值连接到TextBox1中

End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click

Dim btn As Button

btn = sender

TextBox1.Text += btn.Text

End Sub

Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click

Dim btn As Button

btn = sender

'在文本框的Text属性后连接一个空格、本按钮的Text属性值和一个空格

TextBox1.Text = TextBox1.Text + " " + btn.Text + " "

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

TextBox1.Text = "" '清空文本框

End Sub

Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click

Dim btn As Button

btn = sender

TextBox1.Text = TextBox1.Text + " " + btn.Text + " "

End Sub

Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click

Dim btn As Button

btn = sender

TextBox1.Text = TextBox1.Text + " " + btn.Text + " "

End Sub

Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click

Dim btn As Button

btn = sender

TextBox1.Text = TextBox1.Text + " " + btn.Text + " "

End Sub

Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click

'发生错误转移到标号“ErrorPro”指定的行去执行错误处理程序

On Error GoTo ErrorPro

Dim r As Decimal '保存计算结果的变量

Dim t As String = TextBox1.Text '用于保存文本框中的算术表达式

Dim space As Integer = t.IndexOf(" ") '搜索空格位置,如果没有空格，返回值为0

'字符串的取子符方法，第二个参数小于0，则将产生错误号为5的异常，即过程参数不正确

Dim s1 As String = t.Substring(0, space) '通过取子串方法获得第一个运算数

Dim op As String = t.Substring(space + 1, 1) '通过取子串方法获得运算符

Dim s2 As String = t.Substring(space + 3) '通过取子串方法获得第二个运算数

Dim arg1, arg2 As Integer

arg1 = Val(s1) : arg2 = Val(s2)

Select Case op

Case "+" : r = arg1 + arg2

Case "-" : r = arg1 - arg2

Case "*" : r = arg1 * arg2

Case "/" : r = arg1 / arg2

Case Else

MsgBox("输入的运算符有误！")

Exit Sub

End Select

TextBox1.Text = CStr(r) '显示结果

Exit Sub '退出过程

ErrorPro: '错误处理程序块

Select Case Err.Number

Case 6 '除数为零时，或运算溢出时的错误号

MsgBox("算术运算溢出！", , "溢出提示")

TextBox1.Focus()

Exit Sub

Case 5 ' Substring过程的参数不符合要求的错误号

MsgBox("必须输入运算符和第二个运算数！", , "运算数少")

Exit Sub

Case Else

'其它情况显示错误号和错误原因

MsgBox("错误号为" Err.Number Chr(10) Chr(13) "错误原因：" Err.Description)

Exit Sub

End Select

End Sub

End Class