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<h1>PHP Error Handling</h1>
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<p class="intro">The default error handling in PHP is very simple. An error message with filename, line
number and a message describing the error is sent to the browser.</p>
<hr />
<h2>PHP Error Handling</h2>
<p>When creating scripts and web applications, error handling is an important
part. If your code lacks error checking code, your program may look very
unprofessional and you may be open to security risks.</p>
<p>This tutorial contains some
of the most common error checking methods in PHP.</p>
<p>We will show different error handling methods:</p>
<ul>
<li>Simple "die()" statements</li>
<li>Custom errors and error triggers</li>
<li>Error reporting</li>
</ul>
<hr />
<h2>Basic Error Handling: Using the die() function</h2>
<p>The first example shows a simple script that opens a text file:</p>
<table width="100%" border="1" class="ex" cellspacing="0" id="table12"><tr><td>
<pre><?php
$file=fopen("welcome.txt","r");
?></pre>
</td></tr></table>
<p>If the file does not exist you might get an error like this:</p>
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<pre><b>Warning</b>: fopen(welcome.txt) [function.fopen]: failed to open stream:
No such file or directory in <b>C:\webfolder\test.php</b> on line <b>2</b></pre>
</td></tr></table>
<p>To avoid that the user gets an error message like the one above, we test if
the file exist before we try to access it:</p>
<table width="100%" border="1" class="ex" cellspacing="0" id="table15"><tr><td>
<pre><?php
if(!file_exists("welcome.txt"))
{
die("File not found");
}
else
{
$file=fopen("welcome.txt","r");
}
?></pre>
</td></tr></table>
<p>Now if the file does not exist you get an error like this:</p>
<table width="100%" border="1" class="ex" cellspacing="0" id="table14"><tr><td>
<pre>File not found</pre>
</td></tr></table>
<p>The code above is more efficient than the earlier code, because it
uses a simple error handling mechanism to stop the script after the error.</p>
<p>However, simply stopping the script is not always the right way to go. Let's take a
look at alternative PHP functions for handling errors.</p>
<hr />
<h2>Creating a Custom Error Handler</h2>
<p>Creating a custom error handler is quite simple. We simply create a special
function that can be called when an error occurs in PHP.</p>
<p>This function must be able to handle a minimum of two parameters (error
level and error message) but can accept up to five parameters (optionally: file,
line-number, and the error context): </p>
<h2>Syntax</h2>
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