I tought you forgot to initializae the $obligatoryFieldNotPresent variable,
as PHP create variables when they are initialized, the
$obligatoryFieldNotPresent variable is created inside the if.
$obligatoryFieldNotPresent = 0;
if (strlen($_POST["titleIN"]) == 0 ) {
$obligatoryFieldNotPresent = 1;
}
elseif (strlen($_POST["first_nameIN"]) == 0 ) {
$obligatoryFieldNotPresent = 1;
}
elseif (strlen($_POST["publisherIN"]) == 0 ) {
$obligatoryFieldNotPresent = 1;
}
elseif (strlen($_POST["copyrightIN"]) == "" ) {
$obligatoryFieldNotPresent = 1;
}
elseif (strlen($_POST["ISBNIN"]) == 0 ) {
$obligatoryFieldNotPresent = 1;
}
elseif (strlen($_POST["languageIN"]) == 0 ) {
$obligatoryFieldNotPresent = 1;
}
elseif (!empty($_POST['categoriesIN'])) {
$obligatoryFieldNotPresent = 0;
}
--
Davi R. Tavares