取得TextBox 某一行的字串
來源:cww

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，並設定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