How to get the digits of a number without converting it to a string/ char array?
The following prints the digits in order of ascending significance (i.e. units, then tens, etc.):
do {
int digit = n % 10;
putchar('0' + digit);
n /= 10;
} while (n > 0);
Since everybody is chiming in without knowing the question.
Here is my attempt at futility:
#include <iostream>
template<int D> int getDigit(int val) {return getDigit<D-1>(val/10);}
template<> int getDigit<1>(int val) {return val % 10;}
int main()
{
std::cout << getDigit<5>(1234567) << "\n";
}
I have seen many answers, but they all forgot to use do {...} while()
loop, which is actually the canonical way to solve this problem and handle 0
properly.
My solution is based on this one by Naveen.
int n = 0;
std::cin>>n;
std::deque<int> digits;
n = abs(n);
do {
digits.push_front( n % 10);
n /= 10;
} while (n>0);
What about floor(log(number))+1
?
With n digits and using base b you can express any number up to pow(b,n)-1
. So to get the number of digits of a number x in base b you can use the inverse function of exponentiation: base-b logarithm. To deal with non-integer results you can use the floor()+1
trick.
PS: This works for integers, not for numbers with decimals (in that case you should know what's the precision of the type you are using).