incorrect answer

[thatwhiteguy]

I have been working on this program for a few days now, and I am at a loss as to what is wrong. I am new to c++, so I am sure that it must be something simple that I am missing, but I can not pin point it. Below is my code, and no matter what I input it gives me the same answer: $1.#INF. All I need for it to do is calculate the monthly payments .


[CODE=cpp]#include <iostream>

using namespace std ;
//function prototype
double payment(double balance, double AIR, int num_of_pay);
//funciton prototype
double power (int num_of_pay, double AIR);
int main ()
{
double month_pay; //
double balance; //amount of loan
double AIR; //annual interest rate
int num_of_pay ; //number of payments over course of loan
double result;

cout<< "Welcome to the loan payment calculator program!"<<endl ;

cout<< " Please enter the loan amount:"<<endl ;
cin>> balance;

cout<< " Please enter the annual interest rate as a percentage, not a decimal:"<<endl ;
cin>> AIR;

cout<< "Please enter number of payments you will pay:"<<endl;
cin>> num_of_pay;
month_pay = payment(balance , AIR, num_of_pay);
cout<< "The amount of your monthly payment is: $" << month_pay <<endl;

system("PAUSE") ;
return (0);
}

double payment(double balance, double AIR, int num_of_pay)
{

double month_pay;

AIR = (AIR/100.00)/12.00;

month_pay = (balance * AIR) / ( 1.0 - power ((! + AIR), -num_of_pay));

return (month_pay);
}


double power (int num_of_pay, double AIR)
{
double result;
int i;

result = 1.0;
for (i=0; i< abs (num_of_pay); i++) result *= (1 + AIR );

if (num_of_pay > 0)
return (result);
else
return (1.0 / result);
}[/CODE]

[mschenkelberg]

what do you pass to the program?

[thatwhiteguy]

what do you pass to the program?

I pass the amount of the loan. We'll say 5700. The amount of interest, we'll say 12 . And the amount of total payments, we'll say 36.

[weaknessforcats]

month_pay = (balance * AIR) / ( 1.0 - power ((! + AIR), -num_of_pay));

So, what's the ! for ??? ............... ............... .......^