<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Basics</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.errors.html">Errors</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.errors.php7.html">Errors in PHP 7</a></div> <div class="up"><a href="language.errors.html">Errors</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="language.errors.basics" class="sect1"> <h2 class="title">Basics</h2> <p class="para"> PHP reports errors in response to a number of internal error conditions. These may be used to signal a number of different conditions, and can be displayed and/or logged as required. </p> <p class="para"> Every error that PHP generates includes a type. A <a href="errorfunc.constants.html" class="link">list of these types</a> is available, along with a short description of their behaviour and how they can be caused. </p> <div class="sect2" id="language.errors.basics.handling"> <h3 class="title">Handling errors with PHP</h3> <p class="para"> If no error handler is set, then PHP will handle any errors that occur according to its configuration. Which errors are reported and which are ignored is controlled by the <a href="errorfunc.configuration.html#ini.error-reporting" class="link"><code class="parameter">error_reporting</code></a> php.ini directive, or at runtime by calling <span class="function"><a href="function.error-reporting.html" class="function">error_reporting()</a></span>. It is strongly recommended that the configuration directive be set, however, as some errors can occur before execution of your script begins. </p> <p class="para"> In a development environment, you should always set <a href="errorfunc.configuration.html#ini.error-reporting" class="link"><code class="parameter">error_reporting</code></a> to <strong><code>E_ALL</code></strong>, as you need to be aware of and fix the issues raised by PHP. In production, you may wish to set this to a less verbose level such as <code class="code">E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED</code>, but in many cases <strong><code>E_ALL</code></strong> is also appropriate, as it may provide early warning of potential issues. </p> <p class="para"> What PHP does with these errors depends on two further php.ini directives. <a href="errorfunc.configuration.html#ini.display-errors" class="link"><code class="parameter">display_errors</code></a> controls whether the error is shown as part of the script's output. This should always be disabled in a production environment, as it can include confidential information such as database passwords, but is often useful to enable in development, as it ensures immediate reporting of issues. </p> <p class="para"> In addition to displaying errors, PHP can log errors when the <a href="errorfunc.configuration.html#ini.log-errors" class="link"><code class="parameter">log_errors</code></a> directive is enabled. This will log any errors to the file or syslog defined by <a href="errorfunc.configuration.html#ini.error-log" class="link"><code class="parameter">error_log</code></a>. This can be extremely useful in a production environment, as you can log errors that occur and then generate reports based on those errors. </p> </div> <div class="sect2" id="language.errors.basics.user"> <h3 class="title">User error handlers</h3> <p class="para"> If PHP's default error handling is inadequate, you can also handle many types of error with your own custom error handler by installing it with <span class="function"><a href="function.set-error-handler.html" class="function">set_error_handler()</a></span>. While some error types cannot be handled this way, those that can be handled can then be handled in the way that your script sees fit: for example, this can be used to show a custom error page to the user and then report more directly than via a log, such as by sending an e-mail. </p> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.errors.html">Errors</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.errors.php7.html">Errors in PHP 7</a></div> <div class="up"><a href="language.errors.html">Errors</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>
