Windows Sockets startup

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/** * main.c * startup Windows Sockets demo * @author  : MJN * @date    : 2011-10-09 */#include < stdio.h >#include < winsock2.h >#pragma comment(lib, "ws2_32")int main(int argc, char* argv[]){    WSADATA wsaData;        /*     * socket version: 2.2     * return 0 if startup success     */    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);    if (iResult != 0)    {        printf("WSAStartup failed with error: %d\n", iResult);        return -1;    }    if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2)     {        /* Tell the user that we could not find a usable */        /* WinSock DLL.                                  */        WSACleanup( );        return -1;     }    printf("WSAStartup succeeded.\n");    printf("version:%x\n", wsaData.wVersion);       /* output: 202 (means 0x0202) */    printf("high version:%x\n", wsaData.wHighVersion);    printf("description:%s\n", wsaData.szDescription);    printf("status:%s\n", wsaData.szSystemStatus);    WSACleanup();    return 0;}

程序输出:

WSADATA的定义如下:

typedef struct WSAData {  WORD           wVersion;  WORD           wHighVersion;  char           szDescription[WSADESCRIPTION_LEN+1];  char           szSystemStatus[WSASYS_STATUS_LEN+1];  unsigned short iMaxSockets;  unsigned short iMaxUdpDg;  char FAR       *lpVendorInfo;} WSADATA, *LPWSADATA;

WSADATA的成员

wVersion:

Ws2_32.dll期望调用者使用的Windows Sockets规范的版本号. 高字节为次版本号, 低字节为主版本号

wHighVersion:Ws2_32.dll支持的最高版本号.

szDescription:

关于Windows Sockets实现的描述

szSystemStatus:

Windows Sockets的状态.

iMaxSockets, iMaxUdpDg, lpVendorInfo:

Windows Sockets版本2及以后的版本, 这三个成员被忽略.

程序在调用Windows socket 函数之前, 需要先初始化Windows socket动态链接库. 函数WSAStartup的声明如下:

int WSAStartup(  __in   WORD wVersionRequested,  __out  LPWSADATA lpWSAData);

参数wVersionRequested是调用者可用的Windows Sockets最高版本号

参考:

1. MSDN

2. NNU姜老师网络编程课件

3. 《TCP/IP协议与网络编程》任泰明编著西安电子科技大学出版社

环境:

1. 开发: Microsoft Visual C++

2. 系统: Windows XP Professional