Count Number of Digits After Decimal in C++

We are given two integer numbers let’s say num1 and num2 and the task is to divide the num1 with num2 and calculate the count of digits after decimal on dividing these given numbers.

For Example

Input − num1 = 2, num2 = 5
Output − count is 1

Explanation − when we divide 2 with 5 i.e. ? = 0.4, so digits after decimal is 1 therefore count is 1.

Input − num1 = 2, num2 = 0
Output − Floating point exception (core dumped)

Explanation − when we divide any number with 0 it will return an error and terminate the program abnormally.

Input − num1 = 2, num2 = 3
Output − Infinite

Explanation − when we divide 2 with 3 i.e. 2/3 = 0.666..., digits after decimal is infinite therefore we will print infinite.

Approach used in the below program is as follows

• Input two variables let’s say, num1 and num2

• Create a variable count to store the count of decimal numbers and initializes it with 0

• Create a variable um of unordered_map type

• Start loop while num1%num2 != 0

• Inside the loop, set num1 with num1%num2

• Increment the value of count by 1

• Check if um.find(num1) != um.end() then return -1

• Outside the loop, return the value in count.

• Print the result.

Example

 Live Demo

#include <iostream>
#include <unordered_map>
using namespace std;
int countdigits(int x, int y){
   int result = 0; // result variable
   unordered_map<int, int> mymap;
   // calculating remainder
   while (x % y != 0){
      x = x % y;
      result++;
      if (mymap.find(x) != mymap.end()){
         return -1;
      }
      mymap[x] = 1;
      x = x * 10;
   }
   return result;
}
int main(){
   int res = countdigits(2, 5);
   (res == -1)? cout << "count is Infinty" : cout <<"count is "<<res;
   return 0;
}

Output

If we run the above code we will get the following output −

count is 1