C++ - how to find the length of an integer

Question

I\'m trying to find a way to find the length of an integer (number of digits) and then place it in an integer array. The assignment also calls for doing this without the use

Answer 1

int intLength(int i) {
    int l=0;
    for(;i;i/=10) l++;
    return l==0 ? 1 : l;
}

Here's a tiny efficient one

Answer 2

Best way is to find using log, it works always

int len = ceil(log10(num))+1;

Answer 3

Being a computer nerd and not a maths nerd I'd do:

char buffer[64];
int len = sprintf(buffer, "%d", theNum);

Answer 4

Not necessarily the most efficient, but one of the shortest and most readable using C++:

std::to_string(num).length()

Answer 5

Would this be an efficient approach? Converting to a string and finding the length property?

int num = 123  
string strNum = to_string(num); // 123 becomes "123"
int length = strNum.length(); // length = 3
char array[3]; // or whatever you want to do with the length

Answer 6

How about (works also for 0 and negatives):

int digits( int x ) { 
    return ( (bool) x * (int) log10( abs( x ) ) + 1 );
}