Re: Take in a command while doing something else
Sam wrote:
Stuart Golodetz writes:
Sam wrote:
Nick W writes:
Hi all,
I will be using a C++ program to control a robot, and would like to
"accept" keyboard-entered commands (strings) while the program is
running and controlling the robot as a part of the control cycle. What
is the best way of doing this please?
The C++ programming language does not define any entity which is
called a "keyboard". Your question is about the specific C++
implementation you are using, rather than the C++ language itself,
and the correct answer to your question depends on your specific C++
implementation and operating system. The answer would be different,
for example, was your application running on Microsoft Windows,
Linux, or Mac.
You can do platform-independent input by just reading from std::cin
surely?
Read OP's original message and pay attention. He is asking for reading
cin only when input is available. poll() or select() is not available
everywhere.
Actually he didn't say that - although I agree it's probably what he'll
ultimately want. I did pay attention to what he did say, which was that
he wanted to accept commands entered at the keyboard and use them to
control the robot. As a very hacked-together example:
#include <iostream>
#include <string>
#include <boost/thread/thread.hpp>
boost::mutex doneMutex;
bool done = false;
void robot_controller()
{
for(;;)
{
boost::mutex::scoped_lock lock(doneMutex);
if(done) break;
// TODO: Do something interesting here
}
}
void user_input()
{
for(;;)
{
std::cout << "Enter a command: ";
std::cout.flush();
std::string cmd;
std::getline(std::cin, cmd);
if(cmd == "quit")
{
boost::mutex::scoped_lock lock(doneMutex);
done = true;
break;
}
}
}
int main()
{
boost::thread rcThread(robot_controller);
boost::thread uiThread(user_input);
rcThread.join();
uiThread.join();
return 0;
}
Best wishes,
Stu
The fact that the specification for the C++ language (note: not the
language itself) doesn't define what a "keyboard" is doesn't mean that
you can't portably get some sort of input from a keyboard (you might not
Yeah, but that was not the original question.
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