zend_error()

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 9.16 shows a list of possible values (see Figure 9.8). These values are also referred to in php.ini. Depending on which error type you choose, your messages will be logged.

Obrßzek 36-1. Table 9.16. Zend's Predefined Error Messages.

Error	Description
`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.

Obrßzek 36-2. Figure 9.8. Display of warning messages in the browser.