I left out reading in the libraries and some other stuff, but I was wondering how long the code below would take to run, I stopped it after like 15 mins because my computer thought it was a virus.
int main(){
double min = __DBL_MIN__;
double current = __DBL_MAX__;
while ( current > min ){
current = current - min;
}
CodePudding user response：
Forever.
current - min rounds to current.
Floating point numbers store value with a floating significand. Do not expect values with an extreme difference in exponential value to perform a subtraction exactly.
CodePudding user response：
To expand a bit on @chux's (correct) answer:
A typical double will have a range of positive numbers from approximately 10-308 to 10 308. But it will only have around 16 significant digits.
That means for a number near 10 308, the smallest number you can subtract that will change the value is approximately 10(308-16) = 10292.
That's only a rough approximation, but somewhere in that vicinity is a lower limit, and any number smaller than that limit can be subtracted from 10308 as often as you like, and the result will remain unchanged.