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<h2 class="title">Error Control Operators</h2>
<p class="simpara">
PHP supports one error control operator: the at sign (@). When
prepended to an expression in PHP, any error messages that might
be generated by that expression will be ignored.
</p>
<p class="simpara">
If you have set a custom error handler function with
<span class="function"><a href="function.set-error-handler.html" class="function">set_error_handler()</a></span> then it will still get
called, but this custom error handler can (and should) call <span class="function"><a href="function.error-reporting.html" class="function">error_reporting()</a></span>
which will return 0 when the call that triggered the error was preceded by an @.
</p>
<p class="simpara">
If the <a href="errorfunc.configuration.html#ini.track-errors" class="link"><strong class="option unknown">track_errors</strong>
</a>
feature is enabled, any error message generated by the expression
will be saved in the variable
<var class="varname"><var class="varname"><a href="reserved.variables.phperrormsg.html" class="classname">$php_errormsg</a></var></var>.
This variable will be overwritten on each error, so check early if you
want to use it.
</p>
<p class="para">
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* Intentional file error */<br /></span><span style="color: #0000BB">$my_file </span><span style="color: #007700">= @</span><span style="color: #0000BB">file </span><span style="color: #007700">(</span><span style="color: #DD0000">'non_existent_file'</span><span style="color: #007700">) or<br /> die (</span><span style="color: #DD0000">"Failed opening file: error was '</span><span style="color: #0000BB">$php_errormsg</span><span style="color: #DD0000">'"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// this works for any expression, not just functions:<br /></span><span style="color: #0000BB">$value </span><span style="color: #007700">= @</span><span style="color: #0000BB">$cache</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">];<br /></span><span style="color: #FF8000">// will not issue a notice if the index $key doesn't exist.<br /><br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<span class="simpara">
The @-operator works only on
<a href="language.expressions.html" class="link">expressions</a>. A simple rule
of thumb is: if you can take the value of something, you can prepend
the @ operator to it. For instance, you can prepend it to variables,
function and <span class="function"><a href="function.include.html" class="function">include</a></span> calls, constants, and
so forth. You cannot prepend it to function or class definitions,
or conditional structures such as <em>if</em> and
<a href="control-structures.foreach.html" class="link">foreach</a>, and so forth.
</span>
</p></blockquote>
<p class="simpara">
See also <span class="function"><a href="function.error-reporting.html" class="function">error_reporting()</a></span> and the manual section for
<a href="ref.errorfunc.html" class="link">Error Handling and Logging functions</a>.
</p>
<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
Currently the "@" error-control operator prefix will even disable
error reporting for critical errors that will terminate script
execution. Among other things, this means that if you use "@" to
suppress errors from a certain function and either it isn't
available or has been mistyped, the script will die right there
with no indication as to why.
</p>
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