Question

C++ programming question. I did the codes but my year result is wrong. Please help me fix this.

Question: The population of a town A is less than the population of a town B. However, the population of town A is growing faster than the population of town B. Write a program that prompts the user to enter the population and growth rate of each town. The program outputs after how many years the population of town A will be greater than or equal to the population of town B and the populations of both towns at that time.

My codes:

#include<iostream>

using namespace std;
int townPopulationA, townPopulationB, year;
double townGrowthRateA, townGrowthRateB, finalA, finalB;

int main()
{
   cout<<"This program is to compare population growth. Town A population is less than Town B.But Town A have higher growth rate\n";
   cout << "Please enter higher population for town B but higher increase for town A\n";

   cout << "Enter the population of Town A: ";
   cin >> townPopulationA;

   cout << "Enter the population of Town B: ";
   cin >> townPopulationB;

   if (townPopulationA < townPopulationB)
   {
       cout << "Enter the growth rate of town A: ";
       cin >> townGrowthRateA;
       cout << "Enter the growth rate of town B: ";
       cin >> townGrowthRateB;
       if (townGrowthRateA <= townGrowthRateB)
       {
           cout << "Your input is invalid";
           return 1;
       }
       else if (townGrowthRateA > townGrowthRateB)
       {
          
               finalA = townPopulationA * (1 + townGrowthRateA / 100.00);
               finalB = townPopulationB * (1 + townGrowthRateB / 100.00);
               year++;

           cout << "Town A Population: " << finalA << endl;
           cout << "Town B Population: " << finalB << endl;
       }
       cout << "After " << year << " year, the population of town A is greater or equal to town B\n";
   }
   else if (townPopulationA > townPopulationB)
   {
       cout << "Your input is invalid";
       return 1;
   }
   system("pause");

}

Answer 1

#include<iostream>

using namespace std;
int townPopulationA, townPopulationB, year;
double townGrowthRateA, townGrowthRateB, finalA=0, finalB=0;

int main()
{
cout<<"This program is to compare population growth. Town A population is less than Town B.But Town A have higher growth rate\n";
cout << "Please enter higher population for town B but higher increase for town A\n";

cout << "Enter the population of Town A: ";
cin >> townPopulationA;

cout << "Enter the population of Town B: ";
cin >> townPopulationB;

if (townPopulationA < townPopulationB)
{
cout << "Enter the growth rate of town A: ";
cin >> townGrowthRateA;
cout << "Enter the growth rate of town B: ";
cin >> townGrowthRateB;
if (townGrowthRateA <= townGrowthRateB)
{
cout << "Your input is invalid";
return 1;
}
else if (townGrowthRateA > townGrowthRateB)
{
  
       finalA = townPopulationA;
       finalB = townPopulationB;
      
       do//iterating upto finalA is greater than or equal to finalB
       {
finalA += finalA * (1 + townGrowthRateA / 100.00);
finalB += finalB * (1 + townGrowthRateB / 100.00);

year++;



  
           }while(finalA<finalB);
  
cout << "Town A Population: " << (int)finalA << endl;
cout << "Town B Population: " <<(int) finalB << endl;

}
cout << "After " << year << " year, the population of town A is greater or equal to town B\n";
}
else if (townPopulationA > townPopulationB)
{
cout << "Your input is invalid";
return 1;
}
//system("pause");

}

output:

This program is to compare population growth. Town A population is less than Town B.But Town A have higher growth rate
Please enter higher population for town B but higher increase for town A
Enter the population of Town A: 200
Enter the population of Town B: 250
Enter the growth rate of town A: 100
Enter the growth rate of town B: 80
Town A Population: 16200
Town B Population: 15366
After 4 year, the population of town A is greater or equal to town B

Process exited normally.
Press any key to continue . . .