C# help to find right solution

Question

The program to analyse a housing loan where the user is to enter the amount of the loan, the annual interest rate,and the duration of the loan in whole number of years. If invalid data has been entered the user should be advise, otherwise use a method to calculate the monthly payment and then display it.

method: private decimal calcMOnthlyPayment(decimal p,doube r,int n)
formula is: payment =p*r/(1-(1+r)^(-n))

where ^ means raised to a power,p is amount of the loan,r is the monthly interest rate, and n is the duration of the loan in month.

The annual interest rate should be a decimal number between 0 and 1and divided by 12.

Thanks for answers for advance..

Iftikar Hussain · Answer

Hi you can do this as shown below private void button1_Click( object sender EventArgs e) { bool isValid = true ; var loanAmountString = textBox1.Text.Trim(); var interestRateString = textBox2.Text.Trim(); var paymentPeriodsString = textBox3.Text.Trim(); if (loanAmountString ==  ) { isValid = false ; lblErrorMessage1.Text = Loan Amount is required ; } else if (!IsValidateNumeric(loanAmountString)) { isValid = false ; lblErrorMessage1.Text = Enter valid Loan Amount (only number) ; } if (interestRateString ==  ) { isValid = false ; lblErrorMessage2.Text = Interest rate is required ; } else if (!IsValidateNumeric(interestRateString)) { isValid = false ; lblErrorMessage2.Text = Enter valid Interest rate (only number) ; } if (paymentPeriodsString ==  ) { isValid = false ; lblErrorMessage3.Text = Tenure is required ; } else if (!IsValidateNumeric(paymentPeriodsString)) { isValid = false ; lblErrorMessage3.Text = Enter valid Tenure (only number) ; } if (isValid) { lblErrorMessage1.Text =  ; lblErrorMessage2.Text =  ; lblErrorMessage3.Text =  ; var interestRate = Convert .ToDouble(interestRateString); var paymentPeriods = Convert .ToInt16( Convert .ToDouble(paymentPeriodsString) * 12); var loanAmount = Convert .ToDouble(loanAmountString); if (interestRate > 1) { interestRate = interestRate / 100; } var payment = (loanAmount * Math .Pow((interestRate / 12) + 1 (paymentPeriods)) * interestRate / 12) / ( Math .Pow (interestRate / 12 + 1 (paymentPeriods)) - 1); payment = Math .Round(payment); lblResult.Text = payment.ToString(); } } private bool IsValidateNumeric( string value) { Regex re = new Regex ( @^[0-9]+$ ); if (re.IsMatch(value)) return ( true ); else return ( false ); } Please let me know if you need more information on this. Regard Iftikar Remember to click Mark as Answer on the post if it helps you.

Iftikar Hussain · Answer

Hi The EMI formula is EMI = (P * R/12) * [ (1+R/12)^N] / [ (1+R/12)^N-1] where P = Principal (loan amount); R = Annual Interest Rate; N = No. of Monthly Instalments http://vindeep.com/Personal/EMICalculation.aspx Regards Iftikar

Alex · Answer

Sorry I cant understand the formula.. Can you explain to me please.

Alex · Answer

thank a lot