Help with simple program

[en_7123]

OK I'm trying to have a simple loop which keeps on printing each number from 1,2,... on a different line and it keeps on doing so until the user enters 'e'.
e.g
for(i=0;i<=9999999999;i++)
{
printf("%d\n",i);
}

It does not take any input from user and keeps on printing but as soon as user presses e the program exits.Any clue how to go about this.

[Cabhan]

This sounds to me a lot like a homework problem. Homework problems are not allowed on this forum.

To me, the easiest solution would seem to be threading, but that may not be for you.

I am going to lock this thread because it sounds like homework: if it's not, please PM me and I will reopen it.


EDIT: Unlocking thread because OP verified that it is not homework.

[Cabhan]

Within every process are a number of what are called threads. These threads run separate instructions (that is, their logic is separate), but they share IO and can share memory as well.

What you could do is have a thread that prints the numbers in a loop, and have a second thread wait for input. When the user enters "e", the waiting thread can kill the looping thread and exit the program.

Actually doing this will be a bit tougher. If you're using C, you can look up the pthreads library, which is what we use to do threading in C. For Java, there are the Thread and Runnable classes to look at. Other languages have their own threading implementations.

[drl]

Hi.

One could define "e" as the interrupt character for the terminal. See man stty, man bash (for builtin trap), and experiment ... cheers, drl

[fredheeks]

You could try the following program:

#include <iostream>
#include <pthread.h>
#include <stdlib.h>

using namespace std;

/*
 * Thread method
 * Will run forever until the program exits
 */
void *threadMethod(void *arg)
{
	for (int i=1; true; i++)	// Count up forever
	{
		cout << i << endl;	// Output the current count
		sleep(1);		// Sleep for 1 second, remove this if you don't want a delay
	}
}

/*
 * Main program entry point
 */
int main(int argc, char* argv[])
{
	pthread_t handle;	// Handle for the thread
	int ret = 0;		// Return code used for thread creation

	cout << "Please press 'e' to exit" << endl;	// Message output before creating the thread

	// Create the thread, storing the handle in 'handle', no custom attributes are used,
	// the method 'threadMethod' will be run as the thread and no arguments are passed in
	ret = pthread_create(&handle, NULL, threadMethod, NULL);
	if (ret != 0 ) {
		cerr << "There was a problem creating the thread" << endl;
		cerr << "Return code is "+ret;
		exit(EXIT_FAILURE);
	} 
	pthread_detach(handle);		// Detach the thread so resources are freed on its exit

	while ('e' != getchar()){}

	exit(EXIT_SUCCESS);
}

save it as test.cpp and compile it with g++ -lpthread test.cpp -o test

You'll have to press e+return to exit, but then capturing unbuffered input from a terminal is a little out of scope of this....