C++ need help fixing to get desired output - c++

Question

I am working on a programming challenge from "Starting Out With C++: Early Objects, 10th Edition". I have the code about halfway done, but the output isn't coming out how it is supposed to be, and I am wondering how to fix it. I have it attached here and the desired output.
#include <iostream>
using namespace std;
int main()
{
float starting_num_of_organisms,
average_daily_population_increase,
size_of_daily_population;
int num_of_days_to_multiply;
cout << "Enter Starting Population: ";
while (!(cin >> starting_num_of_organisms) || starting_num_of_organisms < 2) {
cout << "Invalid. Population must be 2 or greater.";
cout << "Enter starting population: ";
cin.clear();
cin.ignore(123, '\n');
}
cout << "Enter positive daily growth % (.1 must be entered as 10): ";
while (!(cin >> average_daily_population_increase) || average_daily_population_increase < 0) {
cout << "Invalid. Daily Population Growth \n"
<< " must be greater than 0. \n"
<< "Enter Daily Population Growth (%): ";
cin.clear();
cin.ignore(123, '\n');
}
average_daily_population_increase *= .01;
cout << "Enter number of days to calculate: ";
while (!(cin >> num_of_days_to_multiply) || num_of_days_to_multiply < 1) {
cout << "Invalid. Number of days must not be less\n"
<< "than 1. Enter number of days to calculate: ";
cin.clear();
cin.ignore(123, '\n');
}
for (int i = 0; i < num_of_days_to_multiply; i++) {
cout << "Population size for day " << (i + 1);
cout << ": " << starting_num_of_organisms
<< endl;
starting_num_of_organisms += (starting_num_of_organisms * average_daily_population_increase);
}
return 0;
}
Here is the current output:
Enter Starting Population: 896.896
Enter positive daily growth % (.1 must be entered as 10): 2.785
Enter number of days to calculate: 8
Population size for day 1: 896.896
Population size for day 2: 921.875
Population size for day 3: 947.549
Population size for day 4: 973.938
Population size for day 5: 1001.06
Population size for day 6: 1028.94
Population size for day 7: 1057.6
Population size for day 8: 1087.05
The desired output is something like this below. The numbers are just for reference, and do not have to be specific to those numbers.
Enter starting population (greater than 2): 896.896
Enter positive daily growth % (.1 must be entered as 10): 2.785
Enter number of days to calculate (greater than 1): 8
----------------------------------
Start Population: 896.90
Daily Percent Growth: 2.79%
Number of Days: 8
Day Start End
Popl. Popl.
----------------------------
1 896.90 921.87
2 921.87 947.55
3 947.55 973.94
4 973.94 1001.06
5 1001.06 1028.94
6 1028.94 1057.60
7 1057.60 1087.05
8 1087.05 1117.33

Answer 1

It appears as though your code does the correct calculations. Just format the output and it will look like the desired output.
printf("%-10s%10s%10s\n", "day", "start", "end");
for(int i = 0; i < 30; i++)
printf("=");
printf("\n");
for (int i = 0; i < num_of_days_to_multiply; i++)
{
printf("%-10u%10.2lf", i + 1, starting_num_of_organisms);
starting_num_of_organisms +=
(starting_num_of_organisms *
average_daily_population_increase);
printf("%10.2lf\n", starting_num_of_organisms);
}
Note I used printf from the C libs (<stdio.h>), but the same can be achieved with cout, just much more verbose.
Output:
Enter Starting Population: 896.896
Enter positive daily growth % (.1 must be entered as 10): 2.785
Enter number of days to calculate: 8
day start end
==============================
1 896.90 921.87
2 921.87 947.55
3 947.55 973.94
4 973.94 1001.06
5 1001.06 1028.94
6 1028.94 1057.60
7 1057.60 1087.05
8 1087.05 1117.33