Windows下匿名管道进程通信

##昨天做网易雷火的一道笔试题，有一个密码锁是由一个函数实现的，函数Y=f(X)；现获得了该函数的一个可执行文件，希望编写代码来测试它##

下载来的可执行文件是一个控制台程序，输入一个浮点数X，会获得相应的Y；

现在希望实现它：

我们假设该可执行文件的源代码（子进程的实现机制）为：

int main(int argc, char* argv[])
{
	double n;
	while (cin >> n)
	{
		cout << 2 * n <<endl;
	}
	
	return 0;
}

实际上我们并不知道f函数的具体实现机制，这里只是模拟。我们将该程序编译链接成：ConsoleApplication1.exe，放于E盘下。

我们需要在主程序里实现进程的通信来完成测试：

//匿名管道进程通信
# include <iostream>
# include <Windows.h>



int main(int argc, char * argv[])
{
	SECURITY_ATTRIBUTES sa;
	sa.nLength = sizeof(SECURITY_ATTRIBUTES);
	sa.lpSecurityDescriptor = NULL;
	sa.bInheritHandle = TRUE;

	HANDLE hParentRead, hChildWrite;
	if (!CreatePipe(&hParentRead, &hChildWrite, &sa, 0)) {
		std::cout<< "Error On CreatePipe()"<<std::endl;
		return 0;
	}

	HANDLE hChildRead, hParentWrite;
	if (!CreatePipe(&hChildRead, &hParentWrite, &sa, 0)) {
		std::cout << "Error On CreatePipe()" << std::endl;
		return 0;
	}

	STARTUPINFO si;
	si.cb = sizeof(STARTUPINFO);
	GetStartupInfo(&si);
	si.hStdError = hChildWrite;
	si.hStdOutput = hChildWrite;
	si.hStdInput = hChildRead;
	//si.wShowWindow = SW_HIDE;
	si.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;

	PROCESS_INFORMATION pi;

	TCHAR * appPath = TEXT("E:\ConsoleApplication1.exe");
	if (!CreateProcess(appPath, NULL, NULL, NULL, TRUE, NULL, NULL, NULL, &si, &pi)) {
		std::cout << "Error on CreateProcess()" << std::endl;
		return 0;
	}

	CloseHandle(hChildWrite);
	CloseHandle(hChildRead);

	double inputdouble;
	std::cin >> inputdouble;

	char buffer[4096];
	sprintf(buffer, "%f", inputdouble);

	DWORD bytesRead;
	if (WriteFile(hParentWrite, &buffer, 4096, &bytesRead, NULL) == NULL)
	{
		std::cout << "Write Failed" << std::endl;
		return 0;
	}
	memset(buffer,0,4096);

	if (ReadFile(hParentRead, buffer, 4095, &bytesRead, NULL) == NULL)
	{
		std::cout << "Read Failed" << std::endl;
		return 0;
	}
	std::cout << buffer;

	
	return 0;
}

在主程序中创建子进程并完成进程间的通信。