  /**//******************************************
 程序名称：socketopt.cpp
程序功能：该程序演示了getsockopt()函数和setsockopt()函数用法
 changshoumeng */
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib,"ws2_32.lib")
void main()
 {
WSADATA wsaData;
SOCKET s;
int optname;//存放选项的值
int optlen;//选项的长度
if(WSAStartup(MAKEWORD(2,2),&wsaData) !=0)
  {
printf("Failed to load winsock. \n");
return;
 }
s = socket(AF_INET,SOCK_STREAM,0);//创建一个套接口
if(s == INVALID_SOCKET)
{
printf("socket() Error \n");
return;
}
optlen = sizeof(optname);
printf("---------------------------\n");
//获得套接口类型
if(getsockopt(s,SOL_SOCKET,SO_TYPE,(char *)&optname,&optlen) ==SOCKET_ERROR)
{
printf("getsockopt() Error: %u \n",WSAGetLastError());
return;
}
printf("以下信息是由getsockopt()函数取得的SO_SOCKET 级别选项实例\n");
switch(optname)
{
case SOCK_STREAM: printf("SO_TYPE:SOCK_STREAM \n");break;
case SOCK_DGRAM : printf("SO_TYPE:SOCK_DGRAM \n");break;
case SOCK_RAW : printf("SO_TYPE:SOCK_RAW \n");break;
}
//获取接收缓冲区的大小
if(getsockopt(s,SOL_SOCKET,SO_RCVBUF,(char *)&optname,&optlen) ==SOCKET_ERROR)
{
printf("getsockopt() Error: %u \n",WSAGetLastError());
return;
}
printf("SO_RCVBUF:%d \n",optname);
//获取发送缓冲区的大小
if(getsockopt(s,SOL_SOCKET,SO_SNDBUF,(char *)&optname,&optlen) ==SOCKET_ERROR)
{
printf("getsockopt() Error: %u \n",WSAGetLastError());
return;
}
printf("SO_SNDBUF:%d \n",optname);
optname = 16*1024;
//重新设置缓冲区的大小
if(setsockopt(s,SOL_SOCKET,SO_RCVBUF,(char *)&optname,sizeof(optname) )== SOCKET_ERROR)
{
printf("setsockopt() Error: %u \n",WSAGetLastError());
return;
}
//获取重新设置的接收缓冲区的大小
if(getsockopt(s,SOL_SOCKET,SO_RCVBUF,(char *)&optname,&optlen) == SOCKET_ERROR)
{
printf("getsockopt() Error: %u \n",WSAGetLastError());
return;
}
printf("---------------------\n");
printf("使用setsockopt()函数设置后再取得的SO_RCVBUF数值\n");
printf("SO_RCVBUF:%d \n",optname);
printf("---------------------\n");
WSACleanup();
}
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