TextBox 是以 vbCr+vbLf 为分行符号， 如果我们要逐一读取 TextBox 每一行， 无非是寻找 vbCr+vbLf 的所在位置， 然后取出每一行的字串， 不过这个方法不快，而且如果我们要读取第 N 行数据，还是要从第 1、2、…N-1 行逐一读起，实在麻烦。 还好 Windows API 提供有读取 TextBox 第 N 行的功能， 细节如下：

1、API 的声明：

Public Const EM_GETLINE = &HC4
Public Const EM_LINELENGTH = &HC1
Public Const EM_LINEINDEX = &HBB

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Private Declare Sub RtlMoveMemory Lib "KERNEL32" (lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)

2. 程序范例：

Sub TB_GetLine(ByVal hWnd As Long, ByVal whichLine As Long, Line As String)

Dim length As Long, bArr() As Byte, bArr2() As Byte, lc As Long

lc = SendMessage(hWnd, EM_LINEINDEX, whichLine, ByVal 0&)

length = SendMessage(hWnd, EM_LINELENGTH, lc, ByVal 0&)

If length > 0 Then
ReDim bArr(length + 1) As Byte,bArr2(length - 1) As Byte
Call RtlMoveMemory(bArr(0), length, 2) '准备一个存储器，传递消息之前先在存储器的前两个字节填入存储器的长度
Call SendMessage(hWnd, EM_GETLINE,whichLine, bArr(0))
Call RtlMoveMemory(bArr2(0), bArr(0), length)
Line = StrConv(bArr2, vbUnicode)
Else
Line = ""
End If

End Sub

' 假设要读取 Text1 第 5 行的数据

Dim S As String

Call TB_GetLine( Text1.hWnd, 5, S )

' 传回值 S 即等于第 5 行的数据

（ 注：TextBox 的行次是从 0 起算。）

站长在去掉有关bArr2的定义后，并将Line=Strconv(bArr2,vbUnicode)改为Line=StrConv(bArr,vbUnicode)发现程序照常运行，似乎bArr2在本程序中是多余的。不知哪位大虾能告知本人bArr2在这里的作用。