vb6调用api写socket 例子

VB6调用API编写Socket可以通过使用WinSock控件或者直接调用Windows API函数来实现。下面是通过调用Windows API函数实现Socket的示例代码：

首先，我们需要在代码的开头添加以下声明：

Private Declare Function socket Lib "ws2_32.dll" (ByVal af As Long, ByVal socktype As Long, ByVal protocol As Long) As Long
Private Declare Function connect Lib "ws2_32.dll" (ByVal s As Long, ByVal name As Long, ByVal namelen As Long) As Long
Private Declare Function send Lib "ws2_32.dll" (ByVal s As Long, ByVal buf As String, ByVal len As Long, ByVal flags As Long) As Long
Private Declare Function recv Lib "ws2_32.dll" (ByVal s As Long, ByVal buf As String, ByVal len As Long, ByVal flags As Long) As Long
Private Declare Function closesocket Lib "ws2_32.dll" (ByVal s As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (dest As Any, src As Any, ByVal length As Long)

接下来，我们可以使用这些函数来编写创建Socket、连接服务器、发送和接收数据的代码。此处以创建一个TCP连接为例：

Private Sub Form_Load()
    Dim serverIP As String
    Dim serverPort As Integer
    Dim sock As Long
    Dim addr As Long
    Dim result As Long
    Dim buffer As String
    Dim size As Long
    
    ' 初始化Winsock库
    WSACleanup
    
    ' 创建Socket
    sock = socket(AF_INET, SOCK_STREAM, 0)
    If sock = 0 Then
        MsgBox "Failed to create socket"
        Exit Sub
    End If
    
    ' 设置服务器地址
    serverIP = "127.0.0.1"
    serverPort = 8080
    
    ' 设置Socket地址
    addr = inet_addr(serverIP)
    
    ' 连接服务器
    CopyMemory ByVal VarPtr(result), ByVal VarPtr(addr), 4
    CopyMemory ByVal VarPtr(result) + 4, ByVal VarPtr(serverPort), 2
    
    result = connect(sock, result, 16)
    If result = -1 Then
        MsgBox "Failed to connect server"
        Exit Sub
    End If
    
    ' 发送数据
    buffer = "Hello, server!"
    size = Len(buffer)
    
    result = send(sock, buffer, size, 0)
    If result = -1 Then
        MsgBox "Failed to send data"
        Exit Sub
    End If
    
    ' 接收数据
    buffer = Space$(1024)
    size = recv(sock, buffer, 1024, 0)
    buffer = Left$(buffer, size)
    MsgBox "Received data: " & buffer
    
    ' 关闭Socket
    closesocket sock
End Sub

在上述代码中，我们首先调用`socket`函数创建一个Socket，然后使用`connect`函数连接到服务器。接下来，使用`send`函数发送数据到服务器，然后使用`recv`函数接收服务器返回的数据。最后，我们使用`closesocket`函数关闭Socket连接。

需要注意的是，上述代码仅用于示例目的，实际应用中可能需要根据具体需求进行适当的修改和完善。