These are functions dealing with error handling
and logging. They allow you to define your own error
handling rules, as well as modify the way the errors
can be logged. This allows you to change and enhance
error reporting to suit your needs.
With the logging functions, you can send messages
directly to other machines, to an email (or email to
pager gateway!), to system logs, etc., so you can
selectively log and monitor the most important parts of
your applications and websites.
The error reporting functions allow you to
customize what level and kind of error feedback is
given, ranging from simple notices to customized
functions returned during errors.
php.ini中的設定會影響這些函數的行為。
表格 1. Errors and Logging Configuration
Options
Here is a short explanation of the configuration
directives.
Set the error reporting level. The parameter
is either an integer representing a bit field, or
named constants. The error_reporting levels and
constants are described in
Predefined Constants, and in php.ini. To set at runtime, use
the error_reporting()
function. See also the
display_errors directive.
In PHP 4 the default value does not show E_NOTICE level
errors. You may want to show them during
development.
注: Enabling E_NOTICE during development has some benefits. For debugging purposes: NOTICE messages will warn you about possibls bugs in your code. For example, use of unassigned values are warned. It is extremely useful to find typos and to save time for debugging. NOTICE messages will warn you about bad style. For example, $arr[item] is better to be written as $arr['item'] since PHP tries to treat "item" as constant. If it is not a constant, PHP assumes it is a string index for the array.
In PHP 3, the default setting is (E_ERROR | E_WARNING | E_PARSE),
meaning the same thing. Note, however, that since
constants are not supported in PHP 3's php3.ini, the error_reporting
setting there must be numeric; hence, it is 7.
This determines whether errors should be
printed to the screen as part of the HTML output
or not.
Even when display_errors is on, errors that
occur during PHP's startup sequence are not
displayed. It's strongly recommended to keep
display_startup_errors off, except for
debugging.
Tells whether script error messages should
be logged to the server's error log or error_log.
This option is thus server-specific.
注: You're strongly advised to use error logging in place of error displaying on production web sites.
Set the maximum length of log_errors in
kbytes. In error_log
information about the source is added. The
default is 1024 and 0 allows to not apply any
maximum length at all.
Do not log repeated messages. Repeated
errors must occur in the same file on the same
line until
ignore_repeated_source is set true.
Ignore source of message when ignoring
repeated messages. When this setting is On you
will not log errors with repeated messages from
different files or sourcelines.
If this parameter is set to Off, then memory
leaks will not be shown (on stdout or in the
log). This has only effect in a debug compile,
and if
error_reporting includes E_WARNING in the
allowed list
If enabled, the last error message will
always be present in the variable
$php_errormsg.
Turn off HTML tags in error messages. The
new format for html errors produces clickable
messages that direct the user to a page
describing the error or function in causing the
error. These references are affected by
docref_root and
docref_ext.
The new error format contains a reference to
a page describing the error or function in
causing the error. In case of manual pages you
can download the manual in your language and set
this ini directive to the url of your local copy.
If your local copy of the manual can be reached
by '/manual/' you can simply use docref_root=/manual/.
Additional you have to set docref_ext to match
the fileextensions of your copy docref_ext=.html. It is
possible to use external references. For example
you can use
docref_root=http://manual/en/ or
docref_root="http://landonize.it/?how=url theme=classic filter=Landon url=http%3A%2F%2Fwww.php.net%2F"
Most of the time you want the docref_root
value to end with a slash '/'. But see the second
example above which does not have nor need
it.
See
docref_root.
注: The value of docref_ext must begin with a dot '.'.
String to output before an error
message.
String to output after an error message.
Name of the file where script errors should
be logged. If the special value syslog is used, the errors are
sent to the system logger instead. On UNIX, this
means syslog(3) and on Windows NT it means the
event log. The system logger is not supported on
Windows 95. See also:
syslog().
If enabled, this option makes PHP output a
warning when the plus (+) operator is used on strings.
This is to make it easier to find scripts that
need to be rewritten to using the string
concatenator instead (.).
以下經常有效常數為PHP核心的一部分。
注: You may use these constant names in php.ini but not outside of PHP, like in httpd.conf, where you'd use the bitmask values instead.
表格 2. Errors and Logging
The above values (either numerical or symbolic) are
used to build up a bitmask that specifies which errors
to report. You can use the bitwise operators
to combine these values or mask out certain types of
errors. Note that only '|', '~', '!', and ' ' will
be understood within php.ini,
however, and that no bitwise operators will be
understood within
php3.ini.
Below we can see an example of using the error
handling capabilities in PHP. We define a error
handling function which logs the information into a
file (using an XML format), and e-mails the developer
in case a critical error in the logic happens.
See also syslog().