Question

IN php ....

I need Help I Need to Modify this application so it uses a persistent session to save the last values entered by the user for 5 minutes.

At the top of the file (before the DOCTYPE html line) you will need to add a section of code which checks to see if a session id exists. If it does not, the code you add (which will be similar to the example on page 359) will need to start a session.

After the above code (and before the DOCTYPE html line) you will need to add a section of code which checks to see if any of the (3) inputs (amount, rate, & years) already exist in $_SESSION[ ]. If they do, you will need to set the initial values for the form fields to those values.

In display_results.php:

At the top of the file you will need to make sure you start the session (see page 358).

After the input field values (amount, rate, & years) are error checked, you will need to store the values in the session (see pp. 360-361)

Remember to display the day/time when your calculation was performed.

My code for the original assignment before its modified to a persistent session.

index.php-->

//set default value of variables for initial page load

if (!isset($investment)) { $investment = ''; }

if (!isset($interest_rate)) { $interest_rate = ''; }

if (!isset($years)) { $years = ''; }

?>

Future Value Calculator

Future Value Calculator

Investment Amount:

value="

">

Yearly Interest Rate:

value="">

Number of Years:

value="">

display_results.php-->

// get the data from the form

$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.';

// 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 = '';

}

// if an error message exists, go to the index page

if ($error_message != '') {

include('index.php');

exit();

}

// 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);

?>

Future Value Calculator

Future Value Calculator

Investment Amount:

Yearly Interest Rate:

Number of Years:

Future Value:

  

  

This calculation was done on echo "" . date("m/d/Y") . "

";

?> at date_default_timezone_set("America/New_York");

echo " " . date("h:i:sa");

?>.

main.css-->

body {

font-family: Arial, Helvetica, sans-serif;

}

main {

display: block;

width: 450px;

margin: 0 auto;

padding: 1em;

background: white;

border: 2px solid navy;

}

h1 {

margin-top: 0;

color: navy;

}

label {

width: 10em;

float: left;

padding-right: 1em;

padding-bottom: .5em;

}

#data input {

float: left;

width: 15em;

margin-bottom: .5em;

}

#buttons input {

float: left;

margin-bottom: .5em;

}

br {

clear: left;

}

.error {

color: red;

font-weight: bold;

}

Answer 1

In index.php will be as below.

<?php
$lifetime = 60 * 5; // 5 mins in seconds
session_set_cookie_params($lifetime, '/');
session_start();
//set default value of variables for initial page load
if (!isset($investment)) { $investment = ''; }
if (!isset($interest_rate)) { $interest_rate = ''; }
if (!isset($years)) { $years = ''; }
if (!empty($_SESSION['amount']))
$investment = $_SESSION['amount'];
if (!empty($_SESSION['rate']))
$interest_rate = $_SESSION['rate'];
if (! empty($_SESSION['year']))
$years = $_SESSION['year'];
?>
<!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 $error_message; ?></p>
<?php } // end if ?>
<form action="display_results.php" method="post">

<div id="data">
<label>Investment Amount:</label>
<input type="text" name="investment"
value="<?php echo $investment; ?>">
<br>

<label>Yearly Interest Rate:</label>
<input type="text" name="interest_rate"
value="<?php echo $interest_rate; ?>">
<br>

<label>Number of Years:</label>
<input type="text" name="years"
value="<?php echo $years; ?>"><br>
</div>

<div id="buttons">
<label>&nbsp;</label>
<input type="submit" value="Calculate"><br>
</div>

</form>
</main>
</body>
</html>

Modify the top part display_result.php as below

<?php
session_start();
// get the data from the form
$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);
  
$_SESSION['amount'] = $investment;
$_SESSION['rate'] = $interest_rate;
$_SESSION['year'] = $years;

// validate investment
........
.........

As you run the application, After submitting index.php by clicking the calculate button, it displays the future value result as shown below.

Now again will be displayed as below.



After pressing calculate button , it gives following display


Now in browser, if the index.php page is invoked, user will get the page with a form filled with value as below.