finding_number_of_digits_in_a_number.cpp

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#include <cassert>   
#include <cmath>     
#include <cstdint>
#include <iostream>  
 
uint64_t finding_number_of_digits_in_a_number(uint64_t n) {
    uint64_t count = 0;  
 
    // iterate until `n` becomes 0
    // remove last digit from `n` in each iteration
    // increase `count` by 1 in each iteration
    while (n != 0) {
        // we can also use `n = n / 10`
        n /= 10;
        // each time the loop is running, `count` will be incremented by 1.
        ++count;
    }
 
    return count;
}
 
double finding_number_of_digits_in_a_number_using_log(double n) {
    // log(0) is undefined
    if (n == 0) {
        return 0;
    }
 
    // to handle the negative numbers
    if (n < 0) {
        n = -n;
    }
 
    double count = floor(log10(n) + 1);
 
    return count;
}
 
static void first_test() {
    assert(finding_number_of_digits_in_a_number(5492) == 4);
    assert(finding_number_of_digits_in_a_number(-0) == 0);
    assert(finding_number_of_digits_in_a_number(10000) == 5);
    assert(finding_number_of_digits_in_a_number(9) == 1);
    assert(finding_number_of_digits_in_a_number(100000) == 6);
    assert(finding_number_of_digits_in_a_number(13) == 2);
    assert(finding_number_of_digits_in_a_number(564) == 3);
}
 
static void second_test() {
    assert(finding_number_of_digits_in_a_number_using_log(5492) == 4);
    assert(finding_number_of_digits_in_a_number_using_log(-0) == 0);
    assert(finding_number_of_digits_in_a_number_using_log(10000) == 5);
    assert(finding_number_of_digits_in_a_number_using_log(9) == 1);
    assert(finding_number_of_digits_in_a_number_using_log(100000) == 6);
    assert(finding_number_of_digits_in_a_number_using_log(13) == 2);
    assert(finding_number_of_digits_in_a_number_using_log(564) == 3);
}
int main() {
    // run self-test implementations
    first_test();
    second_test();
    std::cout << "All tests have successfully passed!\n";
    return 0;
}