integer division vs regular division

问题

I need to compare an integer in a loop to the quotient of a long and a long. in order to not do integer division, if I understand correctly do I need to convert one of the longs into a double?

long prime = primes[d];
int i = 1;

//  "inputNumber / prime" should not be integer division, while it is now.
//  How do I do this yet still compare it to an "int" afterwards? 
while (i < (inputNumber / prime))
{
    primes[i*prime] = 0;
    i++;
}

That's the code snippet. primes is an array filled with longs. Btw is this code correct:

primes[i*prime] = 0;

because I am worried that a long * int won't work for an array index.

Thanks so much!

回答1:

You can multiply one of the operands of the integer division by 1.0 to avoid integer truncation of the result.

回答2:

Why not while((i * prime) < inputNumber) instead? A long multiplied by an int results in a long...

来源：https://stackoverflow.com/questions/11277986/integer-division-vs-regular-division