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>set_error_handler</H1
><DIV
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><A
NAME="AEN17034"
></A
><P
> (PHP 4 >= 4.0.1)</P
>set_error_handler --
Sets a user-defined error handler function.
</DIV
><DIV
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><A
NAME="AEN17037"
></A
><H2
>Description</H2
>string <B
CLASS="methodname"
>set_error_handler</B
> ( string error_handler)<BR
></BR
><P
> Sets a user function (<TT
CLASS="parameter"
><I
>error_handler</I
></TT
>) to handle
errors in a script. Returns the previously defined error handler (if
any), or <TT
CLASS="constant"
><B
>FALSE</B
></TT
> on error. This function can be used for defining your own
way of handling errors during runtime, for example in applications in
which you need to do cleanup of data/files when a critical error happens,
or when you need to trigger an error under certain conditions (using
<A
HREF="function.trigger-error.html"
><B
CLASS="function"
>trigger_error()</B
></A
>)
</P
><P
> The user function needs to accept 2 parameters: the error code, and a
string describing the error. The example below shows the handling of
internal execptions by triggering errors and handling them with a user
defined function:
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></A
><P
><B
>Ejemplo 1.
Error handling with <B
CLASS="function"
>set_error_handler()</B
> and
<A
HREF="function.trigger-error.html"
><B
CLASS="function"
>trigger_error()</B
></A
>
</B
></P
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><PRE
CLASS="php"
><?php
// redefine the user error constants - PHP4 only
define (FATAL,E_USER_ERROR);
define (ERROR,E_USER_WARNING);
define (WARNING,E_USER_NOTICE);
// set the error reporting level for this script
error_reporting (FATAL + ERROR + WARNING);
// error handler function
function myErrorHandler ($errno, $errstr) {
switch ($errno) {
case FATAL:
echo "<b>FATAL</b> [$errno] $errstr<br>\n";
echo " Fatal error in line ".__LINE__." of file ".__FILE__;
echo ", PHP ".PHP_VERSION." (".PHP_OS.")<br>\n";
echo "Aborting...<br>\n";
exit -1;
break;
case ERROR:
echo "<b>ERROR</b> [$errno] $errstr<br>\n";
break;
case WARNING:
echo "<b>WARNING</b> [$errno] $errstr<br>\n";
break;
default:
echo "Unkown error type: [$errno] $errstr<br>\n";
break;
}
}
// function to test the error handling
function scale_by_log ($vect, $scale) {
if ( !is_numeric($scale) || $scale <= 0 )
trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale",
FATAL);
if (!is_array($vect)) {
trigger_error("Incorrect input vector, array of values expected", ERROR);
return null;
}
for ($i=0; $i<count($vect); $i++) {
if (!is_numeric($vect[$i]))
trigger_error("Value at position $i is not a number, using 0 (zero)",
WARNING);
$temp[$i] = log($scale) * $vect[$i];
}
return $temp;
}
// set to the user defined error handler
$old_error_handler = set_error_handler("myErrorHandler");
// trigger some errors, first define a mixed array with a non-numeric item
echo "vector a\n";
$a = array(2,3,"foo",5.5,43.3,21.11);
print_r($a);
// now generate second array, generating a warning
echo "----\nvector b - a warning (b = log(PI) * a)\n";
$b = scale_by_log($a, M_PI);
print_r($b);
// this is trouble, we pass a string instead of an array
echo "----\nvector c - an error\n";
$c = scale_by_log("not array",2.3);
var_dump($c);
// this is a critical error, log of zero or negative number is undefined
echo "----\nvector d - fatal error\n";
$d = scale_by_log($a, -2.5);
?></PRE
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>
And when you run this sample script, the output will be
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></P
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><TD
><PRE
CLASS="programlisting"
>vector a
Array
(
[0] => 2
[1] => 3
[2] => foo
[3] => 5.5
[4] => 43.3
[5] => 21.11
)
----
vector b - a warning (b = log(PI) * a)
<b>WARNING</b> [1024] Value at position 2 is not a number, using 0 (zero)<br>
Array
(
[0] => 2.2894597716988
[1] => 3.4341896575482
[2] => 0
[3] => 6.2960143721717
[4] => 49.566804057279
[5] => 24.165247890281
)
----
vector c - an error
<b>ERROR</b> [512] Incorrect input vector, array of values expected<br>
NULL
----
vector d - fatal error
<b>FATAL</b> [256] log(x) for x <= 0 is undefined, you used: scale = -2.5<br>
Fatal error in line 16 of file trigger_error.php, PHP 4.0.1pl2 (Linux)<br>
Aborting...<br></PRE
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>
</P
><P
> See also <A
HREF="function.error-reporting.html"
><B
CLASS="function"
>error_reporting()</B
></A
>,
<A
HREF="function.restore-error-handler.html"
><B
CLASS="function"
>restore_error_handler()</B
></A
>,
<A
HREF="function.trigger-error.html"
><B
CLASS="function"
>trigger_error()</B
></A
>, <A
HREF="function.user-error.html"
><B
CLASS="function"
>user_error()</B
></A
>
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