问题描述

vb与c#之间通信，VB不能正常接收数据

两个程序之间用WM_COPYDATA方法传递数据，现在VB向c#发送数据，c#可以正常接收（不管VB发送的数据有多长）；c#向VB发送的数据长度小于50，VB能正常接收。问题是c#向VB发送的数据长度大于50的话，VB只能接收前50个，不知道问题出现在哪，请各位高手帮忙看一下，也可qq联系我45262121，另源程序代码附上

解决方案

最好把vb接收部分的代码贴一下，把API和结构体的声明类型贴出来。

解决方案二：

VB接收部分的代码：
Function WndProc(ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Dim l As Long, sData As String
If Msg = WM_COPYDATA Then
pRecData = VarPtr(DatrStruct)
CopyMemory DatrStruct, ByVal lParam, LenB(DatrStruct)
Form1.Text3 = DatrStruct.lpData
Else
WndProc = CallWindowProc(prevWndProc, hWnd, Msg, wParam, lParam)
End If
End Function
VB的api和结构体声明类型如下：
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByRef lParam As Any) As Long

Public Declare Function SendMessageByString Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long

Public Declare Function SendMessageByNum Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Public Declare Function postMessage Lib "user32" Alias "PostMessageA" _
(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long

Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Public Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" _
(ByVal hWnd As Long, ByVal lpString As String, ByVal cch As Long) As Long

Public Declare Function GetWindowTextLength Lib "user32" Alias "GetWindowTextLengthA" _
(ByVal hWnd As Long) As Long

Public Declare Function GetClassName Lib "user32" Alias "GetClassNameA" _
(ByVal hWnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long

Public Declare Function EnumWindows Lib "user32" _
(ByVal lpEnumFunc As Long, ByVal lParam As Any) As Long

Public Declare Function EnumChildWindows Lib "user32" _
(ByVal hwndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Any) As Long

Public Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" _
(ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
(ByVal hWnd As Long, ByVal nIndex As Long) As Long

Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
(ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(pDst As Any, pSrc As Any, ByVal ByteLen As Long)

Public Const GWL_WNDPROC = (-4)
Public Const WM_USER = &H400
Public Const WM_GETTEXTLENGTH = &HE
Public Const WM_SETTEXT = &HC 'Setting text of child window
Public Const WM_GETTEXT = &HD 'Getting text of child window
Public Const WM_COPYDATA As Long = &H4A
Public Const IPC_PLAYFILE = 200
Public frmText As String, frmHwnd As Long
Public CtlText As String '控件文字
Public Txthwnd As Long '要用SendMessage发送消息的控件的句柄
Public pRecData As Long

Public sData As String
Public prevWndProc As Long
Public Type COPYDATASTRUCT
dwData As Long '结构长度,传lenb(DatrStruct)
cbData As Long '后面指针所指内容的长度,传lenb([字符串])
lpData As String '声明为一个String,然后直接赋值为字符串变量就行.
End Type
Public DatrStruct As COPYDATASTRUCT
Public DataStruct As COPYDATASTRUCT