You want to make sure a value has been supplied for a form element, i.e. a field is not left blank.
Use strlen() to test the element in $_GET or $_POST.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<head>
<title>PHP</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
function display_form() {
echo <<<HTML
<form action = "$_SERVER[SCRIPT_NAME]" method="post">
Enter first name
<input type="text" name="first_name" />
<input type="submit" value="Submit" />
</form>
HTML;
}
// Make sure that the first_name field exists before checking its length
if (isset($_POST['first_name']) && strlen($_POST['first_name']) ) {
echo 'Hello, '.$_POST['first_name'], '<br />';
}
else {
echo "You must enter your first name.";
display_form();
}
?>
</p>
</body>
</html>
|
You want to make sure that the length of the input field has a limit.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<head>
<title>PHP</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
function display_form() {
echo <<<HTML
<form action = "$_SERVER[SCRIPT_NAME]" method="post">
Enter first name
<input type="text" name="first_name" />
<input type="submit" value="Submit" />
</form>
HTML;
}
// Make sure that the first_name field exists and has less than 10 characters
if ((isset($_POST['first_name']) && strlen($_POST['first_name'])<=10 )) {
echo 'Hello, '.$_POST['first_name'];
}
else {
echo "Your first name does not exceed 10 characters.";
display_form();
}
?>
</p>
</body>
</html>
|