[Program to count digits in an integer](https://www.geeksforgeeks.org/program-count-digits-integer-3-different-methods) More...

#include <cassert>
#include <cmath>
#include <iostream>

Include dependency graph for finding_number_of_digits_in_a_number.cpp:

Functions
uint64_t	finding_number_of_digits_in_a_number (uint64_t n)
	for IO operations

double	finding_number_of_digits_in_a_number_using_log (double n)
	This function finds the number of digits in constant time using logarithmic function TC: O(1)

static void	first_test ()
	Self-test implementations.

static void	second_test ()

int	main ()
	Main function.

Detailed Description

[Program to count digits in an integer](https://www.geeksforgeeks.org/program-count-digits-integer-3-different-methods)

Author: aminos 🇮🇳

It is a very basic math of finding number of digits in a given number i.e, we can use it by inputting values whether it can be a positive/negative value, let's say: an integer. There is also a second method: by using "K = floor(log10(N) + 1)", but it's only applicable for numbers (not integers). The code for that is also included (finding_number_of_digits_in_a_number_using_log). For more details, refer to the Algorithms-Explanation repository.

Function Documentation

◆ finding_number_of_digits_in_a_number()

uint64_t finding_number_of_digits_in_a_number ( uint64_t n )

for IO operations

for assert for log calculation

The main function that checks the number of digits in a number. TC : O(number of digits)

Parameters

n	the number to check its digits

Returns: the digits count

< the variable used for the digits count

                                                          {
    uint64_t count = 0;  ///< the variable used for the digits count
 
    // 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;
}

◆ finding_number_of_digits_in_a_number_using_log()

double finding_number_of_digits_in_a_number_using_log ( double n )

This function finds the number of digits in constant time using logarithmic function TC: O(1)

Parameters

n	the number to check its digits

Returns: the digits count

                                                                {
    // 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;
}

◆ first_test()

static void first_test ( )

static

Self-test implementations.

Returns: void

                         {
    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);
}

Here is the call graph for this function:

◆ main()

int main ( void )

Main function.

Returns: 0 on exit

           {
    // run self-test implementations
    first_test();
    second_test();
    std::cout << "All tests have successfully passed!\n";
    return 0;
}