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Chapter 3 - Question 10

Design a program to compute the balance of a deposit account at the end of a given period when the interest rate and initial balance are known.

Solution 1

Example use:

C:\code>Interest 3
Starting balance is 188. Interest rate is 4%
Balance after 1 month(s) is 195.52
Balance after 2 month(s) is 203.341
Balance after 3 month(s) is 211.474
Final balance is 211.474
C:\code>
#include <time.h>
#include <math.h>
#include <iostream.h>
 
using namespace std;
 
int main(int argc, char *argv[])
{
   // make sure random numbers are random
   srand(time(NULL));
   rand();
 
   // the amount of months is given by the user
   int iMonths = atoi(argv[1]);    
   // generate a random interest rate
   // between 0.5 and 5 in 0.5 increments
   float fInterest = (10 * rand()) / RAND_MAX;
   fInterest /= 2;
   // generate a random starting balance
   // between 1 and 2000
   float fBalance = ((2000 * rand()) / RAND_MAX)+1;
   
   // i've already used iostream.h, but i prefer printf
   cout << "Starting balance is " << fBalance << " Interest rate is " << fInterest << "%\n";
   // now loop through each month and add interest to the total
   for (int n = 1; n <= iMonths; n++)
   {
       // add up the interest for this month
       fBalance += fBalance * (fInterest / 100);
       // show the balanace after this many months
       cout << "Balance after " << n << " month(s) is " << fBalance << "\n";
   }
   // show the final balance
   cout << "Final balance is " << fBalance;
}
 

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