Programming PHP

To turn off error reporting entirely, use:
error_reporting(0);
This ensures that, regardless of the errors encountered while processing and executing
your script, no errors will be sent to the client (except parse errors, which cannot
be suppressed). Of course, it doesn’t stop those errors from occurring. Better options
for controlling which error messages are displayed in the client are shown in the section
“Defining Error Handlers.”
Triggering Errors
You can throw an error from within a script with the trigger_error( ) function:
trigger_error(message [, type]);
The first parameter is the error message; the second, optional, parameter is the condition
level, which is either E_USER_ERROR, E_USER_WARNING, or E_USER_NOTICE (the
default).
Triggering errors is useful when writing your own functions for checking the sanity
of parameters. For example, here’s a function that divides one number by another
and throws an error if the second parameter is zero:
function divider($a, $b) {
if($b == 0) {
trigger_error('$b cannot be 0', E_USER_ERROR);
}
return($a / $b);
}
echo divider(200, 3);
echo divider(10, 0);
66.666666666667
Fatal error: $b cannot be 0 in page.php on line 5
Defining Error Handlers
If you want better error control than just hiding any errors (and you usually do), you
can supply PHP with an error handler. The error handler is called when a condition
of any kind is encountered and can do anything you want it to, from logging to a file
to pretty-printing the error message. The basic process is to create an error-handling
function and register it with set_error_handler( ).
The function you declare can take in either two or five parameters. The first two
parameters are the error code and a string describing the error. The final three parameters,
if your function accepts them, are the filename in which the error occurred, the
line number at which the error occurred, and a copy of the active symbol table at the
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