how to break an infinity loop from external?

[draggy]

hi...

let's say i have an infinty loop:

int main()
{
      while(true)
      {
           //... blah blah
       }

}

how to break of the loop externally?

using interrupt?

thanks

[dwks]

Have a variable, like quit, which is usually zero. When you want to quit, set it to one.

Or else you can just check the return values of your functions.

[mitakeet]

If something inside your loop blocks, you will need to use signals.

[draggy]

void t1()
{
	while(true)
	{
		//point b
	}
}

int main()
{
            bool bk = false;
	char c;

	while(!bk)
	{
		//point a
		scanf("%c", &c)
		if(c == 'y' || c == 'Y')
			bk = true;
		
		t1();
	}
	
}

based on the code basically when it come to point b... it will be forever stuck there...... now my question i s how to break it.. if point b is not implemented any signal handler or etc etc....?

Thanks

[mitakeet]

You must have a break in the point b loop or it will run forever, it is that simple. How to break it is entirely up to you.

[dwks]

You know what mitakeet means, right?

while(1) {
    //...
    c = getinput();
    if(c == 'x') break;
    //...
}

[draggy]

You know what mitakeet means, right?

while(1) {
    //...
    c = getinput();
    if(c == 'x') break;
    //...
}

ya i know....... but how do we break something like this:

while(1) {
    //...
    //...
}

that's the problem......

[mitakeet]

Why not post some real code?

[Dave_Sinkula]

how to break of the loop externally?

I may be reading this wrong, but is this what you are asking: "Let's say we have the following code. How do I stop it; how do I break out of running the program?"

#include <stdio.h>
#include <string.h>

int main(void)
{
   for ( ;; )
   {
      char line[80];
      fputs("enter some text: ", stdout);
      fflush(stdout);
      if ( fgets(line, sizeof line, stdin) )
      {
         char *newline = strchr(line, '\n');
         if ( newline )
         {
            *newline = '\0';
         }
         printf("line = \"%s\"\n", line);
      }
   }
   return 0;
}

/* my output
enter some text: hello world
line = "hello world"
enter some text: okay, now what?
line = "okay, now what?"
enter some text: hey -- how do I stop this thing?
line = "hey -- how do I stop this thing?"
enter some text: ^C
*/

Here in Windows I pressed Ctrl+C. Ctrl+Break works as well.

[draggy]

sorry for the late reply.... a bit busy over here..
ok ...

example:

int main()
{
	while(true)
	{
		//point b
		//without break or loop terminator
	}
}

ok above is a infinity loop, which can't be terminate unless using Crtl + c....

As we can see most OS have the ability to manage and terminate any task by send a message or command or etc etc.....

My question is how to terminate the infinty loop, where we at outside the boundry of that infinty loop or program......

thanks

[quzah]

How about:

volatile int terminate = 0;

while( !terminate )
{
    ...
}

Now you just have 'terminate' modified by something else, and you're all set. Otherwise:

My question is how to terminate the infinty loop, where we at outside the boundry of that infinty loop or program......

This doesn't make any sense. If you're "outside the boundry of that ... loop", then how again do you need to terminate it? If you're not within the bounds of said loop, there's nothing to terminate. Your entire program doesn't run every single instruction all at the same time. It happens sequentially.


Quzah.

[dwks]

Perhaps exit()?

[jverkoey]

Optionally you could use a thread?

e.g. The infinity loop is in the thread:

while(1)
{
  // stuff
}

Main wants to stop the loop, so it kills the thread.