setsockopt(s,SOL_SOCKET,SO_RCVBUF,(char*)&rcvbuf,sizeof(int));

示例：

#ifndef _MY_SOCKET_#define _MY_SOCKET_#ifdef WIN32#include <Windows.h>#include <WinSock.h>#else#include <sys/socket.h>#include <sys/types.h>#endifclass Socket{public:	enum EMode{BLOCKING,NOBLOCKING};public:	Socket();	~Socket();	int Connect(char *destaddr,unsigned short port);	int Bind(char *paddr,int port);	int Listen();	int Accept();	void Ioctlsocket(EMode mode);	void SetBufferSize();	int RecvData(char *recvbuf,int len);	int SendData(char *sendbuf,int len);private:	int s;//監聽socket	int socks;//建聯socket};#endif
#include "Socket.h"Socket::Socket(){#ifdef WIN32	/* 加載socket dll 庫，第一個調用的函數	WSAStartup(Word wVersionRequired,LPWSADATA lpWSAData);	wVersionRequired:動態庫版本,MAKEWORD(X,Y)指定參數;	lpWSAData:動態庫相關信息*/	LPWSADATA lpWSAData={0};	int iRet=WSAStartup(MAKEWORD(2,2),&lpWSAData);	if(iRet!=0){		WSACleanup();	}	#else 	#endif	s=socket(AF_INET,NULL,SOCK_STREAM);			  }Socket::~Socket(){	closesocket(s);}int Socket::Bind(char* paddr,int port){	sockaddr_in severaddr;	severaddr.sin_addr.s_addr=inet_addr(paddr);	severaddr.sin_family=AF_INET;	severaddr.sin_port=htons(port);	return bind(s,(sockaddr*)&severaddr,sizeof(severaddr));}int Socket::Connect(char *destaddr,unsigned short port){	sockaddr_in server;	server.sin_addr.s_addr=inet_addr(destaddr);	server.sin_family=AF_INET;	server.sin_port=htons(port);	return connect(s,(sockaddr*)&server,sizeof(server));}int Socket::Listen(){	listen(s,4);}int Socket::Accept(){	sockaddr_in client;	int client_len=sizeof(client);	/*client 內容接受后客戶填充*/	int socks=accept(s,(sockaddr*)&client,&client_len);	if(socks==-1){		return false;	}	return true;}void Socket::Ioctlsocket(EMode mode){	/*ioctlsocket(s,long cmd,u_long* argp);	cmd:輸入輸出控制命令，FIONBIO,FIONREAD,SIOCATMARK;	argp:指向cmd指針;	FIONBIO:默認從阻塞模式轉非阻塞，或者相反轉變,*argp=TRUE(非0)，socket變非阻塞，*argp=FALSE（0)，socket阻塞;	*/	if(mode==EMode::NOBLOCKING)	{		unsigned long ul=1;		ioctlsocket(s,FIONBIO,(unsigned long*)&ul);	}	else{		unsigned long ul=0;		ioctlsocket(s,FIONBIO,(unsigned long*)&ul);	}	}void Socket::SetBufferSize(){	long rcvbuf=1024*10;	setsockopt(s,SOL_SOCKET,SO_RCVBUF,(char*)&rcvbuf,sizeof(long));}int Socket::RecvData(char *recvbuf,int len){	return recv(s,recvbuf,len,0);}int Socket::SendData(char *sendbuf,int len){	return send(s,sendbuf,len,0);}