The output isnt correct.

[mattkeem]

#include "amort.h" 
#include <stdio.h>
#include <stdlib.h>
#include <process.h>
#include<ctype.h>
#include<conio.h>

//extern double getPaymentAmount(double principal,int numberOfMonths,double interest);
//extern double getLoanAmount(double payment,int numberOfMonths,double interest);
//extern int getNumberOfMonths(double payment, double principal,double interest);

int main(void)
{
	
	int choice;
	int	numberOfMonths;
	int months;
	float interest;
	double principal;
	double payment;

	do
	{
		system("cls");
		printf("Welcome to Amortization Calculator by Yongho Kim\n");
		printf("==========================================\n");
		printf("1.calculate size of payments\n");
		printf("2.calculate size of the loan\n");
		printf("3.calculate number of payments\n");
		printf("4.exit\n");
		printf("==========================================\n");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1:
			printf("Enter annual interest rate: ");
			scanf("%f",&interest);
			while(interest<=0)
			{

				printf("annual interest rate should be >0: ");
				scanf("%f",&interest);
			}
			printf("\nInterest rate: %.2f\n",interest);
			printf("Enter principal amount: ");
			scanf("%lf",&principal);
			printf("\nPrincipal amount:$ %.2f\n",principal);
			printf("Enter number of months: ");
			scanf("%d",&numberOfMonths);
			printf("\nNumber of months: %d\n",numberOfMonths);
			payment = getPaymentAmount(interest,numberOfMonths,principal/1200);
			printf("Payment Amount=$ %.2lf",payment);
			break;
	
			case 2:
			printf("Enter annual interest rate: ");
			scanf("%lf",&interest);
			while(interest<=0)
			{
				printf("annual interest rate should be >0: ");
				scanf("%lf",&interest);
			}
			printf("\nInterest rate:$ %.2f\n",interest);
			printf("Enter payment amount: ");
			scanf("%lf",&payment);
			printf("\nPayment amount:$ %.2f\n",payment);
			printf("Enter number of months: ");
			scanf("%d",&numberOfMonths);
			printf("\nNumber of months: %d\n",numberOfMonths);
			principal = getLoanAmount(payment,numberOfMonths,interest/1200);
			printf("Principal Amount=$ %.2lf",principal);
			break;
	
			case 3:
			printf("Enter annual interest rate: ");
			scanf("%lf",&interest);
			while(interest<=0)
			{
				printf("annual interest rate should be >0: ");
				scanf("%lf",&interest);
			}
			printf("\nInterest rate:$ %.2f\n",interest);
			printf("Enter principal amount: ");
			scanf("%lf",&principal);
			printf("\nPrincipal amount:$ %.2f\n",principal);
			printf("Enter payment amount: ");
			scanf("%d",&payment);
			printf("\nPayment amount:$ %.2f\n",payment);
			months = getNumberOfMonths(payment,principal,interest/1200);
			printf("NUmber of months= %d",months);
			break;
	
			case 4:
			return 1;
		}
		printf("\n\n\n\nWould you like to start over? Y/N");
	}while( getch() == 'y' || getch() == 'Y');

	return 1;
}



=====================

#include "amort.h" 
#include <math.h>
//----------------------------------------------------------------------------
//
//----------------------------------------------------------------------------
double getPaymentAmount(double interest, int numberOfMonths, double principal)
{
	double numerator,denominator;
		numerator= powf((1+interest),numberOfMonths)*principal*interest;
		denominator=powf((1+interest),numberOfMonths)-1;

	return numerator/denominator;
}
//----------------------------------------------------------------------------
//
//----------------------------------------------------------------------------
double getLoanAmount(double interest, int numberOfMonths, double payment)
{
	double numerator,denominator;
		numerator=powf((1+interest),numberOfMonths) - 1*payment;
		denominator=interest*powf((1+interest),numberOfMonths);

	return numerator/denominator;

}
//----------------------------------------------------------------------------
//
//----------------------------------------------------------------------------
int getNumberOfMonths(double interest, double payment, double principal)
{
	double numerator,denominator;
		numerator=log(payment)-log(payment-(principal*interest));
		denominator=log(1+interest);

	return numerator/denominator;
}



===============

#ifndef AMORT_H
#define AMORT_H
#include <math.h>

#pragma once

	double getPaymentAmount(double principal,int numberOfMonths,double interest);
	double getLoanAmount(double payment,int numberOfMonths,double interest);
	int getNumberOfMonths(double payment, double principal,double interest);

#endif

the output that im suppose to get isnt right... it keeps giving me random numbers or too high. can someone help me with this??
and is there a way to calcuclate the interest and print it on the console system?

[Atheist]

You are way to vague in your problem description. What exactly is your code supposed to do? What output are you expecting?

[mattkeem]

Payment amount and interest. User inputs three informations

[ForumAccount]

I didn't see this thread until now. I posted in your other thread. Please refrain from re-posting the same question.