zend_error() can be used to generate error messages. This function accepts two arguments; the first is the error type (see zend_errors.h), and the second is the error message.
zend_error(E_WARNING, "This function has been called with empty arguments");
Table 36-1. Zend's Predefined Error Messages.
|E_ERROR||Signals an error and terminates execution of the script immediately .|
|E_WARNING||Signals a generic warning. Execution continues.|
|E_PARSE||Signals a parser error. Execution continues.|
|E_NOTICE||Signals a notice. Execution continues. Note that by default the display of this type of error messages is turned off in php.ini.|
|E_CORE_ERROR||Internal error by the core; shouldn't be used by user-written modules.|
|E_COMPILE_ERROR||Internal error by the compiler; shouldn't be used by user-written modules.|
|E_COMPILE_WARNING||Internal warning by the compiler; shouldn't be used by user-written modules.|