thank you in advance for any insight you might provide on this. I am new to PHP just started this week.
I have two pages index.php and result.php
I have copied the php portion from the result.php in order to display the result of a calculation within the same page.
The calculation is working fine, but I cannot set the input values to empty strings after the result of the calculation displayed below the form.
Index.php
<?php
//set default value of variables for initial page load this portion was
//previously set within the index.php
if (!isset($investment)) { $investment = ''; }
if (!isset($interest_rate)) { $interest_rate = ''; }
if (!isset($years)) { $years = ''; }
//Copied this code from the result.php
$investment = filter_input(INPUT_POST, 'investment',
FILTER_VALIDATE_FLOAT);
$interest_rate = filter_input(INPUT_POST, 'interest_rate',
FILTER_VALIDATE_FLOAT);
$years = filter_input(INPUT_POST, 'years',
FILTER_VALIDATE_INT);
// validate investment
if ($investment === FALSE ) {
$error_message = 'Investment must be a valid number.';
} else if ( $investment <= 0 ) {
$error_message = 'Investment must be greater than zero.';
// validate interest rate
} else if ( $interest_rate === FALSE ) {
$error_message = 'Interest rate must be a valid number.';
} else if ( $interest_rate <= 0) {
$error_message = 'Interest rate must be greater than zero .';
} else if ( $interest_rate > 15 ) {
$error_message = 'Interest rate must be less than or equal to 15.';
// validate years
} else if ( $years === FALSE ) {
$error_message = 'Years must be a valid whole number.';
} else if ( $years <= 0 ) {
$error_message = 'Years must be greater than zero.';
} else if ( $years > 30 ) {
$error_message = 'Years must be less than 31.';
// set error message to empty string if no invalid entries
} else {
$error_message = '';
}
// calculate the future value
$future_value = $investment;
for ($i = 1; $i <= $years; $i++) {
$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($future_value, 2);
//End of copied from the result.php copy
?>
<!DOCTYPE html>
<html>
<head>
<title>Future Value Calculator</title>
<link rel="stylesheet" type="text/css" href="main.css">
</head>
<body>
<main>
<h1>Future Value Calculator</h1>
<?php if (!empty($error_message)) { ?>
<p class="error"><?php echo htmlspecialchars($error_message); ?></p>
<?php } ?>
<form id="myform" action="<?php $_SERVER['PHP_SELF'];?>" method="post">
<div id="data">
<label>Investment Amount:</label>
<input type="text" name="investment"
value="<?php echo htmlspecialchars($investment); ?>">
<br>
<label>Yearly Interest Rate:</label>
<input type="text" name="interest_rate"
value="<?php echo htmlspecialchars($interest_rate); ?>">
<br>
<label>Number of Years:</label>
<input type="text" name="years"
value="<?php echo htmlspecialchars($years); ?>">
<br>
</div>
<div id="buttons">
<label> </label>
<input type="submit" value="Calculate"><br>
</div>
</form>
<!--copied from the result.php-->
<label>Investment Amount:</label>
<span><?php echo htmlspecialchars($investment_f); ?></span><br />
<label>Yearly Interest Rate:</label>
<span><?php echo htmlspecialchars($yearly_rate_f); ?></span><br />
<label>Number of Years:</label>
<span><?php echo htmlspecialchars($years); ?></span><br />
<label>Future Value:</label>
<span><?php echo htmlspecialchars($future_value_f); ?></span><br />
<p>This calculation was done on <?php echo date('m/d/Y'); ?>.</p>
</main>
</body>
</html>if anybody could point me in the right direction I would be extremely grateful.
</div>
