Listening to stdin while performing certain operations

[Horsey]

Hi!

I'm trying to write a program, based on following ideas:
- while not interrupted, program is performing some operations, then goes in sleep/wait state for a minute, then again - operations, and sleep/wait state...
- if interrupted (user inserts a command), program handles the command and then goes back to his work/sleep loop.

My question is if there is a way to make my program sleep, but at the same time monitor standard input, to handle the command immediately if given. I would rather not create two thread application.

Big thanks in advance!

[edit]
Ah, of course: I'm looking rather for a C++ solution.

[Salem]

Windows or Linux?

[Horsey]

Linux.

Thanks for moving thread to the correct board.

[Salem]

select(2): synchronous I/O multiplexing - Linux man page
- create an fd set for stdin
- create a timeout for 1 minute

Look at the return result to decide whether it was a timeout of some input.

[Horsey]

Big thanks, Salem.

However, I must admit, I lied a bit... I said I need linux command, because I'm compiling under MinGW, and I hoped the answer would be proper also for this. Unfortunately it seems that select() is one of POSIX functions, which MinGW doesn't support (damn, damn, damn...).

So I need to apologize and re-ask: could you help me find select() equivalent which would work under MinGW?

<edit>
I found something... I think.

It is a Winsock2.h select() function, which is similar to the Unix one.
(need to add -lws2_32 switch to make it link under MinGW)

The code I've written has one serious bug: the program doesn't go to sleep. I don't know if it is because I passed the descriptor/time in the wrong way, but it keeps looping just as if the select function didn't work.

Could you help me with that?

#include <iostream>
#include <Winsock2.h>
using namespace std;
int main(){		
			/*
			this, I believe is creating a fd_set structure with one element pointing at Standard Input 
			std::cin should have 0 as his descriptor
			*/
			fd_set set = {1, {0}};//
		
		/*
		I'm not sure if both values should be equal or not, but it is a positive number
		*/
			timeval time = {5000, 5000000};

			while (1){
			
			cout<<"I start looping!!"<<endl;
			
				int i = select (0, &set, NULL, NULL, &time); //Now the process *should* go to sleep for 5 seconds or more.
				
				if (i == 0) cout <<"It's timeout!"<<endl; //if i!=, it means that the input woke the process, not timeout
			
			}
}