设置connect超时

首先设置socket为非阻塞模式

再通过select查询超时

#include "stdafx.h"
#include <WINSOCK2.H>
#include <stdio.h>
#pragma comment(lib,"ws2_32.lib")
int main(int argc, char* argv[])
{
	WSADATA wsaData;
	if (WSAStartup(MAKEWORD(2,2),&wsaData)!=0)
	{
		return -1;
	}
	PHOSTENT phst=gethostbyname("www.yahoo.com");
	if (!phst)
	{
		return -1;
	}
	IN_ADDR addr;
	memmove(&addr,phst->h_addr_list[0],phst->h_length);
	SOCKADDR_IN Rtaddr;
	Rtaddr.sin_family=AF_INET;
	Rtaddr.sin_addr=addr;
	Rtaddr.sin_port=htons(80);
	SOCKET s=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
	if (s==INVALID_SOCKET)
	{
		return -1;
	}
	DWORD dwset=1;
	int ret=ioctlsocket(s,FIONBIO,(LPDWORD)&dwset);
	if (ret==SOCKET_ERROR)
	{
		return -1;
	}
	DWORD start=GetTickCount();
	connect(s,(SOCKADDR*)&Rtaddr,sizeof Rtaddr);
	
	timeval timeout;
	fd_set r;
	FD_ZERO(&r);
	FD_SET(s,&r);
	timeout.tv_sec=1;
	timeout.tv_usec=0;
	
	ret=select(0,0,&r,0,&timeout);
	if (ret<=0) //超时或SOCKET_ERROR
	{
		printf("connect error.../n");
	}
	else
	printf("connect success./n");
	printf("time: %d/n",GetTickCount()-start);
	dwset=0;
	ret=ioctlsocket(s,FIONBIO,(LPDWORD)&dwset);
	if (ret==SOCKET_ERROR)
	{
		printf("error %d/n",WSAGetLastError());
	}
	closesocket(s);
	WSACleanup();
	return 0;
}