取得TextBox某一行的字串

這是使用EM_GETLINE message來做，比較奇特的是lParam是指向一個字串所在的位置， 但是該字串傳入時，前兩個Byte要存該字串允許的最大長度。  
'以下在Form需一個TextBox，并設定MultiLine = True, 一個Command Button  
Private Sub Command1_Click()  
Dim str5 As String  
str5 = GetaLine(Text1,1)  '取得第二行的字串，以0為基底  
End Sub  

'以下在.Bas  
Option Explicit  
Const EM_GETLINE = &HC4  
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _  
        (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, _  
         lParam As Any) As Long  
Public Function GetaLine(Text1 As TextBox, ByVal ntx As Long) As String  
Dim str5(255) As Byte '如果您的字串 > 255 byte請自行增加該Byte Array  
Dim str6 As String, i As Long  

str5(0) = 255 '字串的前兩個Byte存該字串的最大長度  
str5(0) = 255  
i = SendMessage(Text1.hwnd, EM_GETLINE, ntx, str5(0))  
If i = 0 Then  
    GetaLine = ""  
Else  
    str6 = StrConv(str5, vbUnicode)  
    GetaLine = Left(str6, InStr(1, str6, Chr(0)) - 1)  
End If  
End Function  

原文轉自：http://www.anti-gravitydesign.com