獲取tcp緩衝區大小 - C++

#include "stdafx.h"
#include <WinSock2.h>
#include <iostream>

#pragma comment(lib,"ws2_32.lib")

int main()
{
	WORD vVersionRequested;
	WSADATA wsaData;
	vVersionRequested = MAKEWORD(1, 1);
	WSAStartup(vVersionRequested, &wsaData);//WSAStartup就是爲了向操作系統說明，我們要用哪個庫文件，讓該庫文件與當前的應用程序綁定，從而就可以調用該版本的socket的各種函數了。

	SOCKET sockClient = socket(AF_INET, SOCK_STREAM, 0);

	int optVal = 0;
	int optLen = sizeof(optVal);

	getsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char *)&optVal, &optLen);

	std::cout << "Recv len = " << optVal << std::endl;
	getsockopt(sockClient, SOL_SOCKET, SO_SNDBUF, (char *)&optVal, &optLen);
	std::cout << "send len = " << optVal << std::endl;
	//設置buff
	optVal = 1024*100;
	setsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&optVal, optLen);
	setsockopt(sockClient, SOL_SOCKET, SO_SNDBUF, (char*)&optVal, optLen);

	// 再次獲取sockClient1對應的內核接收緩衝區大小
	getsockopt(sockClient, SOL_SOCKET, SO_RCVBUF, (char*)&optVal, &optLen);
	printf("sockClient, recv buf is %d\n", optVal);
	getsockopt(sockClient, SOL_SOCKET, SO_SNDBUF, (char *)&optVal, &optLen);
	std::cout << "send len = " << optVal << std::endl;

	closesocket(sockClient);
	WSACleanup();

    return 0;
}