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.

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

ErrorDescription
E_ERRORSignals an error and terminates execution of the script immediately.
E_WARNINGSignals a generic warning. Execution continues.
E_PARSESignals a parser error. Execution continues.
E_NOTICESignals a notice. Execution continues. Note that by default the display of this type of error messages is turned off in php.ini.
E_CORE_ERRORInternal error by the core; shouldn't be used by user-written modules.
E_COMPILE_ERRORInternal error by the compiler; shouldn't be used by user-written modules.
E_COMPILE_WARNINGInternal warning by the compiler; shouldn't be used by user-written modules.

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