Int Value does not print?

Question

I have created two thread using and

static int counter (global variable) ;
-(void)ViewDidLoad {
    [NSThread detachNewThreadSelector:@selector(handleTread:) toTarget:self withObject:nil];
    [NSThread detachNewThreadSelector:@selector(handleTread:) toTarget:self withObject:nil];
}

and selector method is

-(void)handleTread:(NSThread*)sender {
    counter =0; // Position-1
    while (counter<9) {
        counter =0; // Position-2
        counter++;
    }
    NSLog(@"Counter=%d",counter);
}

So if I use counter at Position-1 it prints the result as counter=9. But I placed it at Position-2 it does not print? I have updated the question.

Answer 1

There are 2 serious errors in your code:

1. You have two threads of execution manipulating the same global variable. One thread will trample over the variable used by the other. For example thread #1 might be able to get counter to 1 and then thread #2 will reset it back to 0 again. The exact behaviour is undefined.

2. You have an infinite loop (you assign counter = 0 within the while statement), even if the code was executed in a single thread it would never complete.

Fundamentally your code is broken and I'm not sure I can say much more about it.