PHP form numbers validation

saintryan · March 7, 2009

Hello all

I'm currently creating a basic form it has various fields in it. One of them is age..

What i am trying to do is when someone submits their age with the form the php scripts validates it's an integer for a start and then check to see if the age is within a certain bracket like >16 but <26.

here is what i have done so far:

test.html

<form action="myform.php" method="post">
<p>Firstname: *** <input type="text" name="firstname" /><br />
Surname: *** 
  <input type="text" name="surname" />
  <br />
Address: 
<input type="text" name="addressone" />
<br />
Postcode: <input type="text" name="postcode" /><br />
E-mail: <input type="text" name="email" /></p>


<p>
Age: ** 
  <input type="number" name="age" /><br />
<br />
<br />
</p>


<p><input type="submit" value="Send it!"></p>
</form>

myform.php

<?php
$firstname = check_input($_POST['firstname'], "Enter you firstname please");
$surname = check_input($_POST['surname'], "Enter you surnname please");
$addressone = check_input($_POST['adressone']);
$postcode = check_input($_POST['postcode']);
$email = check_input($_POST['email']);
$age = check_input($_POST['vage'], "Please enter your age");

function check_input($data, $error='')
{
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    if ($error && strlen($data) == 0) 
    {
        show_error($error);
    }
   else return $data;
}


function show_error($myError) 
{
?>
    <html>
    <body>

    <b>Please correct the following error:</b><br />
    <?php echo $myError; ?>

    </body>
    </html>
<?php
exit(); 
}
?>

<html>
<body>

Your first name is: <?php echo $firstname; ?><br />
Your Surname is: <?php echo $surname; ?><br />
Your address is: <?php echo $addressone; ?><br />
Your Postcode is: <?php echo $postcode; ?><br />
Your e-mail: <?php echo $email; ?><br />
<br />
<br />
Your age is: <?php echo $age; ?><br />


</body>
</html>

Later on i wish to also add a drop down field aswell to be validated that the right choice has been selected..

If anyone could help me or point me to a tutorial that deals with exactly this i would be most greatful.

MatthewJ · March 7, 2009

http://us3.php.net/is_numeric

For a drop down, you usually just set a default field of "Select One" or something like that and make its value something you can check for like zero, so then you can use

if($_POST['whatever'] == 0) {
//Drop down item not selected
} else {
//Drop down item selected so do something with it
}

pcw · March 7, 2009

<?php

$age = $_POST['age'];

if ($age > 16 && $age < 26 )
{
print "age ok";
}
else
{
print "wrong age";
}

print <<<END
<form method="POST">
age: <input type="text" name="age">
<input type="submit" name="submit" value="submit">
END;

?>

Thats how you would check the age is correct

redarrow · March 7, 2009

strlen($data) == 0 <<< what you mean with this statement there no length?

explain please.

saintryan · March 7, 2009

strlen($data) == 0 <<< what you mean with this statement there no length?

explain please.

yeah if the string length is = to 0 then throw up an error message

I am very new to php and followed at pho form guide... my updated myform code is as follows:

<?php
$firstname = check_input($_POST['firstname'], "Enter you firstname please");
$surname = check_input($_POST['surname'], "Enter you surnname please");
$addressone = check_input($_POST['adressone']);
$postcode = check_input($_POST['postcode']);
$email = check_input($_POST['email']);
$age = check_input($_POST['age'], "Please enter your age");

if (is_numeric($age > 16 && $age < 26))
{
return $age;
}
else
{
print ("age not valid");
}

?>
<html>
<body>

Your first name is: <?php echo $firstname; ?><br />
Your Surname is: <?php echo $surname; ?><br />
Your address is: <?php echo $addressone; ?><br />
Your Postcode is: <?php echo $postcode; ?><br />
Your e-mail: <?php echo $email; ?><br />
<br />
<br />
Your age is: <?php echo $age; ?><br />


</body>
</html>
<?php
function check_input($data, $error='')
{
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    if ($error && strlen($data) == 0) 
    {
        show_error($error);
    }
   else return $data;
}


function show_error($myError) 
{
?>
    <html>
    <body>

    <b>Please correct the following error:</b><br />
    <?php echo $myError; ?>

    </body>
    </html>
<?php
exit(); 
}
?>

i've included an if statement for the age question... but it still does not work? i think it needs to work with the check_input function i created... to bring back the custom error message if the age entered is incorrect, else return the data entered...

i am still able to enter a string into the age field and it comes back.

anyone please?

Philip · March 7, 2009

if (is_numeric($age > 16 && $age < 26))

that is incorrect syntax

if (is_numeric($age) && $age > 16 && $age < 26)

saintryan · March 7, 2009

if (is_numeric($age > 16 && $age < 26))

that is incorrect syntax

if (is_numeric($age) && $age > 16 && $age < 26)

Hello

Thanks for that.

However the result still allows to bring back a string value.. i think i am doing something wrong with my check_input function?? and maybe the age check should be in there? but i'm not sure how?

also if i put in a correct age... i get a blank screen??

thanks again

pcw · March 7, 2009

You need to process the age differently

<?php
$age = $_POST['age'];

if ($age == "") {
print "Please enter your age"
}
elseif(is_numeric($age) && $age > 16 && $age < 26)
{
return $age;
}
else
{
print ("age not valid");
}
?>

as its validity is different from check_input

Philip · March 7, 2009

You wouldn't need to use the check_input function on the age check.

You could also use intval()

saintryan · March 7, 2009

Hi.. well ive just basically created another function called check_age which pretty much does the same job as the check data function exept i put my if statements in there so the code now looks like:

<?php
$firstname = check_input($_POST['firstname'], "Enter you firstname please");
$surname = check_input($_POST['surname'], "Enter you surnname please");
$addressone = check_input($_POST['adressone']);
$postcode = check_input($_POST['postcode']);
$email = check_input($_POST['email']);
$age = check_age($_POST['age'], "Please enter your age");

?>
<html>
<body>

Your first name is: <?php echo $firstname; ?><br />
Your Surname is: <?php echo $surname; ?><br />
Your address is: <?php echo $addressone; ?><br />
Your Postcode is: <?php echo $postcode; ?><br />
Your e-mail: <?php echo $email; ?><br />
<br />
<br />
Your age is: <?php echo $age; ?><br />


</body>
</html>
<?php
function check_age($age, $error='')
{
$data = htmlspecialchars($data);
if (is_numeric($age) && $age > 16 && $age < 26)
{
 show_error($error);
}
else return $age;
}

function check_input($data, $error='')
{
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    if ($error && strlen($data) == 0) 
    {
        show_error($error);
    }
   else return $data;
}


function show_error($myError) 
{
?>
    <html>
    <body>

    <b>Please correct the following error:</b><br />
    <?php echo $myError; ?>

    </body>
    </html>
<?php
exit(); 
}
?>

this kind of works.... but i am still able to enter a string into the age field and its gets through.... what am i doing wrong? am i on the right track?

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PHP form numbers validation

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