Express Positive Integer Number in Words in C++

Suppose we are given a positive integer number. We have to spell the number in words; like if a number "56" is given as input the output will be "Fifty-Six". The range of conversion is up to a billion.

So, if the input is like input = 5678, then the output will be Five Thousand Six Hundred Seventy-Eight.

To solve this, we will follow these steps −

• Define an array ‘numbers’ that contain pairs such as − {{"Billion", 1000000000},
  • {"Million", 1000000},
  • {"Thousand", 1000},
  • {"Hundred", 100},
  • {"Ninety", 90},
  • {"Eighty", 80},
  • {"Seventy", 70},
  • {"Sixty", 60},
  • {"Fifty", 50},
  • {"Forty", 40},
  • {"Thirty", 30},
  • {"Twenty", 20},
  • {"Nineteen", 19},
  • {"Eighteen", 18},
  • {"Seventeen", 17},
  • {"Sixteen", 16},
  • {"Fifteen", 15},
  • {"Fourteen", 14},
  • {"Thirteen", 13},
  • {"Twelve", 12},
  • {"Eleven", 11},
  • {"Ten", 10},
  • {"Nine", 9},
  • {"Eight", 8},
  • {"Seven", 7},
  • {"Six", 6},
  • {"Five", 5},
  • {"Four", 4},
  • {"Three", 3},
  • {"Two", 2},
  • {"One", 1}}
• Define a function solve(). This takes input.
  • if input is same as 0, then −
    • return "Zero"
  • for each num in array numbers, do
    • if second value of num <= input, then −
      • if second value of num >= 100, then −
        • result := solve(input / second value of num)
        • if input > (input / second value of num) * second value of m, then −
          • result := result + " " + solve(input - (input / second value of num))
      • otherwise,
        • result := first value of num + ((if input > second value of num , then: " " + solve(input - second value of num), otherwise: " "))
      • Come out from the loop
  • return result
• solve(input)

Example

Let us see the following implementation to get better understanding −

#include<bits/stdc++.h>

using namespace std;

vector<pair<string, int>> numbers{{"Billion", 1000000000},
   {"Million", 1000000},
   {"Thousand", 1000},
   {"Hundred", 100},
   {"Ninety", 90},
   {"Eighty", 80},
   {"Seventy", 70},
   {"Sixty", 60},
   {"Fifty", 50},
   {"Forty", 40},
   {"Thirty", 30},
   {"Twenty", 20},
   {"Nineteen", 19},
   {"Eighteen", 18},
   {"Seventeen", 17},
   {"Sixteen", 16},
   {"Fifteen", 15},
   {"Fourteen", 14},
   {"Thirteen", 13},
   {"Twelve", 12},
   {"Eleven", 11},
   {"Ten", 10},
   {"Nine", 9},
   {"Eight", 8},
   {"Seven", 7},
   {"Six", 6},
   {"Five", 5},
   {"Four", 4},
   {"Three", 3},
   {"Two", 2},
   {"One", 1}};
string solve(int input) {
   if (input == 0) return "Zero";
   string result;
   for (auto& num : numbers) {
      if (num.second <= input) {
         if (num.second >= 100) {
            result = solve(input / num.second) + " " + num.first;
            if (input > (input / num.second) * num.second)
               result += " " + solve(input - (input / num.second) * num.second);
         } else {
            result = num.first + (input > num.second ? " " + solve(input - num.second) : "");
         }
         break;
      }
   }
   return result;
}

int main() {
   cout<< solve(5678) <<endl;
   return 0;
}

Input

5678

Output

Five Thousand Six Hundred Seventy Eight