Checking progress efficiently | C++

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Hello everyone,

I'm working with a function that, for instance, does some task it it's own thread and takes the address of an int for progress. Like so:

void doSometing(int* progress)

So, While the function is off running, I need an efficient way to check the progress for completion so that I may process the next item. I was doing something like this:

while(progress < 100)
{
    progressBar->value = progress
}

while(progress < 100)
{
    progressBar->value = progress
}

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That just seems like a bit much. But if I only check it every, say, 10 seconds, I could conceivably be wasting 9 seconds for every item. So, is there an accepted way to do something like this?

Thanks for your time,
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