執行個體048文本查找與替換

Strings.InStr 方法

https://docs.microsoft.com/zh-cn/dotnet/api/microsoft.visualbasic.strings.instr?redirectedfrom=MSDN&view=netframework-4.8#overloads

傳回一個整數，該整數指定一個字元串在另一個字元串中的第一個比對項的起始位置。 如果找到了比對項，則該整數是從 1 開始的索引。 如果未找到比對項，則函數傳回零。

控件	屬性	值	控件	屬性	值
TextBox	Name	txtText	Button	Name	btnSearch
Multiline	true	Text	查找
HideSelection	False	Button	Name	btnRaplace
Size	288，232	Text	替換
Location	0，0	Button	Name	btnExit
Text	退出

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        txtText.Text = "Hello,how are you."
    End Sub

    Public Function FindWord(ByVal substring As String) As Boolean
        Dim TextString As String = txtText.Text
        If substring.Equals("") Then
            Return False
        End If
        Dim StartPosition As Integer
        StartPosition = InStr(TextString, substring)
        If StartPosition > 0 Then
            txtText.SelectionStart = StartPosition - 1
            txtText.SelectionLength = Len(substring)
            Return True
        Else
            Return False
        End If

    End Function


    Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
        Dim results As Boolean
        Dim substring As String
        substring = Trim(InputBox("輸入要查找的字元串", "查找", txtText.SelectedText))
        If substring.Equals("") Then
            Exit Sub
        End If
        MsgBox("要查找的字元串是：" & substring)
        results = FindWord(substring)
        If Not results Then
            MsgBox("文本框中沒有要找的字元串")
        End If
    End Sub

    Private Sub btnReplace_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnReplace.Click
        Dim result As Boolean
        Dim substring As String
        If txtText.SelectedText.Equals("") Then
            substring = Trim(InputBox("輸入要查找的字元串", "替換", txtText.SelectedText))
            result = FindWord(substring)
            If Not result Then
                MsgBox("文本框中沒有要找的文本")
                Exit Sub
            End If
        End If
        substring = Trim(InputBox("把找到的文本替換為", "替換", txtText.SelectedText))
        If substring.Equals("") Then
            Exit Sub
        End If
        txtText.SelectedText = substring
    End Sub

    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub
End Class