PHP supports one error control operator: the at sign (@).
When prepended to an expression in PHP, any diagnostic error that might
be generated by that expression will be suppressed.
If a custom error handler function is set with set_error_handler(), it will still be called even though the diagnostic has been suppressed.
Prior to PHP 8.0.0, the error_reporting() called inside the custom error handler
always returned 0 if the error was suppressed by the @ operator.
As of PHP 8.0.0, it returns the value of this (bitwise) expression:
E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR | E_RECOVERABLE_ERROR | E_PARSE.
Any error message generated by the expression is available in the "message"
element of the array returned by error_get_last().
The result of that function will change on each error, so it needs to be checked early.
<?php
/* Intentional file error */
$my_file = @file ('non_existent_file') or
die ("Failed opening file: error was '" . error_get_last()['message'] . "'");
// this works for any expression, not just functions:
$value = @$cache[$key];
// will not issue a notice if the index $key doesn't exist.
?>Note: The
@-operator works only on expressions. A simple rule of thumb is: if one can take the value of something, then one can prepend the@operator to it. For instance, it can be prepended to variables, functions calls, certain language construct calls (e.g. include), and so forth. It cannot be prepended to function or class definitions, or conditional structures such asifand foreach, and so forth.
Prior to PHP 8.0.0, it was possible for the @ operator
to disable critical errors that will terminate script execution.
For example, prepending @ to a call of a function
which did not exist, by being unavailable or mistyped, would cause
the script to terminate with no indication as to why.