Make Contact Form Fields Required

I have a very simple contact form in HTML which posts action to the mail.php page which contains the following code

<?
function checkOK($field)
{
if (eregi("\r",$field) || eregi("\n",$field)){
die("Invalid Input!");
}
}

$name=$_POST['name'];
checkOK($name);
$email=$_POST['email'];
checkOK($email);
$site=$_POST['site'];
checkOK($site);
$budget=$_POST['budget'];
checkOK($budget);
$comments=$_POST['comments'];
checkOK($comments);

$to="[I]HIDDEN FOR DP[/I]";
$message="$name just filled in your Contact Form.
Additional Info (optional): \n$comments\n\nTheir e-mail address is: $email 
Their budget is $budget
Their website is $site";
if(mail($to,"Comments From Your Site",$message,"From: $email\n")) {
echo "Thanks for Contacting us. ";
} else {
echo "There was a problem sending the mail. Please check that you filled in the form correctly.";
}
?>

PHP:

I would like to make some of the fields required as I keep getting blank emails, can anyone help?

Cheers,
Glen

 

Use a plain old JS:

http://javascript.internet.com/forms/required-fields.html

 

You could change the checkOK function so it checks more than it is currently, like this:

function checkOK($field)
{
if (eregi("\r",$field) || eregi("\n",$field) || $field == NULL){
die("Invalid Input!");
}
}

Code (markup):

This should now check each field to see if it is blank, and if it is, it tells the user that the input is invalid. If you don't want all the fields to be checked, add another function that checks only whether a field is blank or not like this:

function checkBlank($field)
{
if ($field == NULL){
die("Invalid Input!");
}
}

Code (markup):

Tell me if this helps!