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    <p>The first one should never be used in production code, since it's transporting information irrelevant to end-users (a user can't do anything about <em>"Cannot connect to database"</em>).</p> <p>You throw Exceptions if you know that at a certain critical code point, your application <em>can fail</em> and you want your code to recover across multiple call-levels.</p> <p><code>trigger_error()</code> lets you fine-grain error reporting (by using different levels of error messages) and you can hide those errors from end-users (using <a href="http://php.net/manual/en/function.set-error-handler.php" rel="noreferrer"><code>set_error_handler()</code></a>) but still have them be displayed to you during testing.</p> <p>Also <code>trigger_error()</code> can produce non-fatal messages important during development that can be suppressed in production code using a custom error handler. You can produce fatal errors, too (<code>E_USER_ERROR</code>) but those aren't recoverable. If you trigger one of those, program execution <em>stops</em> at that point. This is why, for fatal errors, Exceptions should be used. This way, you'll have more control over your program's flow:</p> <pre><code>// Example (pseudo-code for db queries): $db-&gt;query('START TRANSACTION'); try { while ($row = gather_data()) { $db-&gt;query('INSERT INTO `table` (`foo`,`bar`) VALUES(?,?)', ...); } $db-&gt;query('COMMIT'); } catch(Exception $e) { $db-&gt;query('ROLLBACK'); } </code></pre> <p>Here, if <code>gather_data()</code> just plain croaked (using <code>E_USER_ERROR</code> or <code>die()</code>) there's a chance, previous <code>INSERT</code> statements would have made it into your database, even if not desired and you'd have no control over what's to happen next.</p>
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    1. POPHP Error handling: die() Vs trigger_error() Vs throw Exception
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    1. USLinus Kleen
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    1. COso out of `trigger_error()` & throwing exceptions: which one should I use & when?
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      1. USCuriousMind
    2. CO@Gaurish See the added example on that.
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      1. USLinus Kleen
    3. COAfter reading your example, I think now I understand the purpose behind throw exception better. Thanks :)
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