Page 2 - [NEW USERS] - Answers to Frequently Asked Questions

function field_validator($field_descr, $field_data, $field_type, $min_length="", $max_length="", $field_required=1) {
    # array for storing error messages
    global $messages;
	
	# first, if no data and field is not required, just return now:
	if(!$field_data && !$field_required){ return; }

	# initialize a flag variable - used to flag whether data is valid or not
	$field_ok=false;

	# a hash array of "types of data" pointing to "regexps" used to validate the data:
	$data_types=array(
		"email"=>"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$",
		"digit"=>"^[0-9]$",
		"number"=>"^[0-9]+$",
		"alpha"=>"^[a-zA-Z]+$",
		"alpha_space"=>"^[a-zA-Z ]+$",
		"alphanumeric"=>"^[a-zA-Z0-9]+$",
		"alphanumeric_space"=>"^[a-zA-Z0-9 ]+$",
		"string"=>""
    );
    
    # check for required fields
    if ($field_required && empty($field_data)) {
        $messages[] = "$field_descr is a required field.";
		return;
    }
    
	# if field type is a string, no need to check regexp:
	if ($field_type == "string") {
		$field_ok = true;
	} else {
		# Check the field data against the regexp pattern:
		$field_ok = ereg($data_types[$field_type], $field_data);		
	}
	
	# if field data is bad, add message:
	if (!$field_ok) {
		$messages[] = "Please enter a valid $field_descr.";
		return;
	}
	
	# field data min length checking:
	if ($field_ok && $min_length) {
		if (strlen($field_data) < $min_length) {
			$messages[] = "$field_descr is invalid, it should be at least $min_length character(s).";
			return;
		}
	}
	
	# field data max length checking:
	if ($field_ok && $max_length) {
		if (strlen($field_data) > $max_length) {
			$messages[] = "$field_descr is invalid, it should be less than $max_length characters.";
			return;
		}
	}
}