Question

I’m reading the book about optimization teckniks. There is not much description or advices in example though. Here’s the thing:

int agag(int a)
{
  static int dfdfdf = 0;
  static int prev_resilt = 0;
  if (dfdfdf == a)
    return prev_result;
  dfdfdf = a;
  a = SomeCalcs();
  prev_result = a;
  return a;
}

The key thing is: if the arguments are the same as in previous calculation, it will return previous result immediately avoiding a hard calculation.
The question is: will these two static variables be existing until the end of program? As i understand, it is a bad thing to have a lot of these?

I know it’s not much optimization. But i’m only concerned about influence of static variables..

Thank you very much for the answers!

Answer 1

The memory used by the static variables will be allocated in the data segment instead of in the heap or stack. This only becomes a problem when you have a large number of static variables since it means that the executable will have to load a much larger data segment from disk.

But the biggest problem with this method is that it only stores a single value. Better to just implement proper memoization if you expect many repeats with the same inputs.