Please help with the problem described in the title.
I'm writing a little thing to find prime numbers.
I'm looking for a really fast method.
I'm a very early beginner.
I have thought of dividing the int by 10 until it equals 0.
I have thought of converting the int into a string and finding length.
Is there a faster way?
Thanks very much in advance.
ceiling ( log(num) / log(10) )
Thanks.Originally Posted by Thantos
Is this method fast?
Is there a faster one?
Would this method work if x is a multiple of 10?
DependsIs this method fast?
ProbablyIs there a faster one?
Try it and seeWould this method work if x is a multiple of 10?
> I have thought of dividing the int by 10 until it equals 0.
Would work
> I have thought of converting the int into a string and finding length.
Also would work.
> Is there a faster way?
Consider
Also, are you generating a whole series of numbers in a for loop, and trying to find the length of each?Code:while ( x >= 10000 ) { x /= 10000 ; count += 4; } while ( x >= 10 ) { x /= 10 ; count += 1; }
Say for ( i = 1 ; i < 100000000 ; i++ ) kind of thing?
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
