Program to calculate number of digits in an integer & sum of numbers of an integer

The following C++ program calculates the the number of digits in a given integer and the sum of all digits of an integer.

 #include <iostream>  
 #include <cmath>  
 using namespace std;  
 /*@author Bishal Acharya  
 The idea of summing the numbers in an integer is to take  
 a division of the number from ones to final units of the number  
 and then take a modulo against 10*/  
 class SumOfInteger {  
  int number;  
  public :  
  int getSummation(int);   
  int numberOfDigits(int);  
 };  
 /*Gets the number of digits in an integer. Have to make  
 sure that we dont calculate log value of 0 */  
 int SumOfInteger::numberOfDigits(int number){  
  int digits = 0;  
  digits = floor(log10(abs (number != 0 ? number :1))) +1;  
  return digits;  
 }  
 /*Returns the sum of numbers in an integer*/  
 int SumOfInteger::getSummation(int number){  
  int noOfDigits;  
  noOfDigits = numberOfDigits(number);  
  int sum =0;  
  int power =0;  
  for(int i=0; i< noOfDigits; i++){      
   power = pow(10,i);  
   sum = sum + (number / power) % 10;  
  }   
  return sum;  
 }  
 int main(){   
  int number = 0;  
  cout << "Enter the number :";  
  cin >> number;  
  int sum =0;  
  SumOfInteger sumObj;  
  sum = sumObj.getSummation(number);  
  cout << "The sum of the integer numbers :" << sum << endl;  
 }  

Output of the given program :-
Enter the number : 123
The sum of the integer numbers : 6

Alternative program to calculate number of digits in an number :-

 #include<iostream>  
 using namespace std;  
 int main(){  
  int number = 0;  
  cout << "Enter the number" << endl;  
  cin >> number;  
  int count;  
  while(number !=0){  
    number = number/10;  
    count++;  
  }  
  cout << "The number of digits in the number is :" << count;  
 }  

Program to reverse the digits in the given number. For eg :- if given number is 123 then the reversed value should be 321

 #include  
 using namespace std;  
 int main(){  
   int number = 0;  
   cout <<"enter the number :"<< endl;  
   cin >> number;  
   int reverse = 0;  
   while(number !=0){  
     reverse = reverse*10 + number%10;  
     number = number%10;  
   }  
 cout <<"The reversed number is :" << reverse;  
 }  

Benchmarks in Java program : Time it took to calculate number of digits in a number with log approach and with while loop approach.

 public static void main(String[] args) {  
           int number = 0;  
           int temp = 0;  
           Random rnd = new Random();  
           int range = 1;  
           while (range < 10) {  
                number = rnd.nextInt();  
                temp = number;  
                System.out.print("Number :" + number + "TimeWhile :");  
                // approach with while loop  
                int count = 0;  
                long now = System.nanoTime();  
                while (number != 0) {  
                     number = number / 10;  
                     count++;  
                }  
                System.out.print((System.nanoTime() - now) / 1000);  
                now = System.nanoTime();  
                double count1 = (Math.log10(Math.abs(temp) == 0 ? 1 : temp)) + 1;  
                System.out.print(": Timelogarithmic :" + (System.nanoTime() - now)  
                          / 1000);  
                System.out.println("");  
                range++;  
           }  
      }  

Output benchmark for 10 random numbers:-

 Number :279590619TimeWhile :2: Timelogarithmic :40  
 Number :878851661TimeWhile :1: Timelogarithmic :3  
 Number :1617859989TimeWhile :1: Timelogarithmic :3  
 Number :195513660TimeWhile :1: Timelogarithmic :7  
 Number :2024673675TimeWhile :1: Timelogarithmic :3  
 Number :478104225TimeWhile :1: Timelogarithmic :3  
 Number :417156389TimeWhile :1: Timelogarithmic :3  
 Number :-104604112TimeWhile :1: Timelogarithmic :3  
 Number :-516925116TimeWhile :3: Timelogarithmic :4  

The benchmark with Java program suggests that while loop approach of dividing the number by 10 each time gives a better response than using the inbuilt logarithmic and absolute functions.

See More :-
Game Of Pigs in C++
swapping two numbers without using the third one