<?php
// get the data from the form
$investment = $_POST['investment'];
$interest_rate = $_POST['interest_rate'];
$years = $_POST['years'];
$monthly_total = $_POST['compound_monthly_interest'];
$compound_monthly_interests =$monthly_total[0];
$compound_monthly_interests = isset($_POST['compound_monthly_interest']);
// validate investment entry
if ( empty($investment) ) {
$error_message = 'Investment is a required field.';
} else if ( !is_numeric($investment) ) {
$error_message = 'Investment must be a valid number.';
} else if ( $investment <= 0 ) {
$error_message = 'Investment must be greater than zero.';
// validate interest rate entry
} else if ( empty($interest_rate) ) {
$error_message = 'Interest rate is a required field.';
} else if ( !is_numeric($interest_rate) ) {
$error_message = 'Interest rate must be a valid number.';
} else if ( $interest_rate <= 0 ) {
$error_message = 'Interest rate must be greater than zero.';
// set error message to empty string if no invalid entries
} else {
$error_message = '';
}
// if an error message exists, go to the index page
if ($error_message != '') {
include('index.php');
exit();
}
if (isset ($_POST['compound_monthly_interest']) && $_POST['compound_monthly_interest']=='Yes'){
echo "Calculation done on a monthly basis.";
}
echo "Monthly calculation not done";
// calculate the future value
$future_value = $investment;
for ($i = 1; $i <= $years; $i++) {
$future_value = ($future_value + ($future_value * $interest_rate *.01));
}
// apply currency and percent formatting
$investment_f = '$'.number_format($investment, 2);
$yearly_rate_f = $interest_rate.'%';
$future_value_f = '$'.number_format($future_value, 2);