如何得到textbox中第n行字符.txt

以电子书的形式收集了VB一些常见问题解决方法,可以很方便的查找自己需要解决的问题.对一些VB初学者很用.

利 用 API的 EM_GETLINE消 息 。 下 面 是 一 个 例 子 ： 
    1、 建 立 两 个 控 件 ： 
    Text Box控 件 Text1， MultiLine属 性 为 True 
    Label控 件 Label1， AutoSize属 性 为 True 
    2、 加 入 以 下 代 码 ： 
     Option Explicit 
     Private Declare Function SendMessage Lib "user32" _ 
     Alias "SendMessageA" _ 
     (ByVal hwnd As Long, _ 
     ByVal wMsg As Long, _ 
     ByVal wParam As Long, _ 
     ByVal lParam As String) _ 
     As Long 
     Private Declare Function lstrlen Lib "kernel32" Alias "lstrlenA" ( _ 
     ByVal lpString As String) As Long 
     Private Const EM_GETLINE = &HC4 
     Private Const EM_GETLINECOUNT = &HBA 
     Private Const EM_GETSEL = &HB0 
     Private Const EM_LINEFROMCHAR = &HC9 
     Private Const EM_LINEINDEX = &HBB 
     Private Const EM_LINELENGTH = &HC1 
     Private Const EM_REPLACESEL = &HC2 
     
     Private Sub Form_Load() 
     With Command1 
     .Caption = "Insert This Text" 
     .Height = 375 
     .Left = 120 
     .Top = 3000 
     .Width = 1455 
     End With 
     
     With Form1 
     .Caption = "Enhanced Text Box Sample Project" 
     .Height = 4485 
     .Width = 6990 
     End With 
     
     With Label1 
     .Height = 195 
     .Left = 120 
     .Top = 240 
     .Width = 3015 
     .WordWrap = True 
     End With 
     
     With Text1 
     .Height = 2655 
     .Left = 3360 
     .Top = 240 
     .Width = 3375 
     End With 
     
     With Text2 
     .Height = 285 
     .Left = 1680 
     .Top = 3000 
     .Width = 5055 
     End With 
     
     End Sub 
     
     Private Sub Command1_Click() 
     Call SendMessage(Text1.hwnd, EM_REPLACESEL, 0, Text2.Text) 
     Label2.Caption = "Copied text is " + Text2.Text 
     ShowInfo 
     End Sub 
     
     Private Sub Text1_KeyUp(KeyCode As Integer, Shift As Integer) 
     ShowInfo 
     End Sub 
     
     Private Sub Text1_MouseMove(Button As Integer, _ 
     Shift As Integer, _ 
     X As Single, _ 
     Y As Single) 
     ShowInfo 
     End Sub 
     
     Private Function ShowInfo() 
     '******************************************************************** 
     ' Purpose: Runs all the functions to get the necessary information 
     ' in order to create the information text string. The text 
     ' string is then displayed in the label control. 
     '******************************************************************** 
     
     Dim strInfo As String 
     Dim lCurPos As Long 
     Dim lCurLineNum As Long, lTotLines As Long, lLineLength 
     Dim lNumBChar As Long 
     Dim sCurLine As String * 25 
     
     'Determine Cursor Position 
     SendMessage Text1.hwnd, EM_GETSEL, VarPtr(lCurPos), 0 
     If Text1.SelLength > 0 Then 
     lCurPos = lCurPos + lstrlen(Text1.SelText) 
     End If 
     
     'Determine Line Number 
     lCurLineNum = SendMessage(Text1.hwnd, EM_LINEFROMCHAR, lCurPos, 0) 
     
     'Determine the Line Length 
     lLineLength = SendMessage(Text1.hwnd, EM_LINELENGTH, lCurPos, 0) 
     
     'Determine the number of characters in lines before current 
     'cursor position. Note that the number of characters includes a 
     'carriage return and line feed characters at the end of each 
     'line. 
     lNumBChar = SendMessage(Text1.hwnd, EM_LINEINDEX, lCurLineNum, 0) 
     
     'Determine Total number of lines 
     lTotLines = SendMessage(Text1.hwnd, EM_GETLINECOUNT, 0, 0) 
     
     'Determine Current Line 
     sCurLine = Space(25) 
     Call SendMessage(Text1.hwnd, EM_GETLINE, lCurLineNum, sCurLine) 
     
     'Display the information 
     strInfo = "Current Line: " + sCurLine + vbLf + _ 
     "Line Length: " + CStr(lLineLength) + _ 
     " Characters" + vbLf + _ 
     "Line Number: " + CStr(lCurLineNum + 1) + _ 
     " of " + CStr(lTotLines) + " Total Lines" + vbLf + _ 
     "Cursor Position: " + CStr(lCurPos) + vbLf + _ 
     "Total Characters in Previous Lines: " + _ 
     CStr(lNumBChar) + vbLf + _ 
     "Selected Length: " + CStr(Text1.SelLength) + vbLf + _ 
     "Selected Text: " + Text1.SelText 
     
     Label1.Caption = strInfo 
     
     End Function 
<END>