You want to alter the error-logging sensitivity on a particular page. This lets you control what types of errors are reported.
To adjust the types of errors PHP complains about, use error_reporting():
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error_reporting(E_ALL); // everything error_reporting(E_ERROR | E_PARSE); // only major problems error_reporting(E_ALL & ~E_NOTICE); // everything but notices |
Every error generated has an error type associated with it. For example, if you try to array_pop() a string, PHP complains that “This argument needs to be an array” because you can only pop arrays.
The error type associated with this message is E_NOTICE, a nonfatal runtime problem.
By default, the error reporting level is E_ALL & ~E_NOTICE, which means all error types except notices. The & is a logical AND, and the ~ is a logical NOT.
However, the php.inirecommended configuration file sets the error reporting level to E_ALL, which is all error
types.
PHP 5.0 introduced a new error level, E_STRICT. Enabling E_STRICT during development has the benefit of PHP alerting you of ways your code could be improved.
You will receive warnings about the use of deprecated functions, along with tips to nudge you in the direction of the latest and greatest suggested methods of coding.
For PHP 5.0–5.3, E_STRICT is the only error level not included in E_ALL; for maximum coverage during development, set the error reporting level to E_ALL | E_STRICT.
Starting with PHP 5.4, E_STRICT is included in E_ALL.
Error messages flagged as notices are runtime problems that are less serious than warnings.
They’re not necessarily wrong, but they indicate a potential problem.
One example of an E_NOTICE is “Undefined variable,” which occurs if you try to use a variable without previously assigning it a value:
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// Generates an E_NOTICE foreach ($array as $value) { $html .= $value; } // Doesn't generate any error message $html = ''; foreach ($array as $value) { $html .= $value; } |
In the first case, the first time through the foreach, $html is undefined. So when you append to it, PHP lets you know you’re appending to an undefined variable.
In the second case, the empty string is assigned to $html above the loop to avoid the E_NOTICE.
The previous two code snippets generate identical code because the default value of a variable is the empty string.
The E_NOTICE can be helpful because, for example, you may have misspelled a variable name:
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foreach ($array as $value) { $hmtl .= $value; // oops! that should be $html } $html = ''; foreach ($array as $value) { $hmtl .= $value; // oops! that should be $html } |
A custom error-handling function can parse errors based on their type and take an appropriate action. A complete list of error types is shown in Table 20-2.
Table 20-2. Error types
| Value | Constant | Description | Catchable |
| 1
2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32767 |
E_ERROR
E_WARNING E_PARSE E_NOTICE E_CORE_ERROR E_CORE_WARNING E_COMPILE_ERROR E_COMPILE_WARNING E_USER_ERROR E_USER_WARNING E_USER_NOTICE E_STRICT E_RECOVERABLE_ERROR E_DEPRECATED E_USER_DEPRECATED E_ALL |
Nonrecoverable error
Recoverable error Parser error Possible error Like E_ERROR but generated by the PHP core Like E_WARNING but generated by the PHP core Like E_ERROR but generated by the Zend Engine Like E_WARNING but generated by the Zend Engine Like E_ERROR but triggered by calling trigger_error() Like E_WARNING but triggered by calling trigger_error() Like E_NOTICE but triggered by calling trigger_error() Runtime notices in which PHP suggests changes to improve code quality (since PHP 5) Dangerous error (such as mismatched type hint) but not fatal Warning that you’ve used a deprecated function or feature Deprecation warning you can trigger in your code Everything |
No
Yes No Yes No No No No Yes Yes Yes N/A Yes Yes Yes No |
Errors labeled catchable can be processed by the function registered using set_error_handler(). The others indicate such a serious problem that they’re not safe to be handled by users, and PHP must take care of them.
The E_RECOVERABLE_ERROR type was introduced in PHP 5.2.0. The E_DEPRECATED and E_USER_DEPRECATED types were introduced in PHP 5.3.0.
