Question

What’s the best way to write

int NumDigits(int n);

in C++ which would return the number of digits in the decimal representation of the input. For example 11->2, 999->3, -1->2 etc etc.

Answer 1

Straightforward and simple, and independent of sizeof(int):

int NumDigits(int n) {
    int digits = 0;
    if (n <= 0) {
        n = -n;
        ++digits;
    }
    while (n) {
        n /= 10;
        ++digits;
    }
    return digits;
}