ch13s05.html
3.09 KB
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Reading binary data from a file</title><link rel="stylesheet" type="text/css" href="manual.css"><meta name="generator" content="DocBook XSL Stylesheets V1.76.0"><link rel="home" href="index.html" title="JpGraph Manual"><link rel="up" href="ch13.html" title="Chapter 13. Getting hold of the data to be displayed"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Reading binary data from a file</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center">Chapter 13. Getting hold of the data to be displayed</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="sect1" title="Reading binary data from a file"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2539067"></a>Reading binary data from a file</h2></div></div></div>
<p>This can be potentially dangerous since the exact format for the binary data can
differ depending on convention and system. The advantage is that it usually gives
smaller data files and is usually not as suspect to data corruption since it is not
easy to read directly into a text editor and change. In PHP a variable can be stored
in a binary format using the <code class="code">serialize()</code> function and read back from a
file with <code class="code">unserialize()</code></p>
<p>
</p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
<p>It is also possible to store binary data in a text file as a string. One
way of doing this is to do a base64 encoding of the binary data. This will
guarantee that the encoded data will only be printable characters which can
be stored in a normal string. One thing to remember is that this will
enlarge the data by roughly 30%. Another example on when base64 encoding is
useful is to store binary images in a text file. This is the way for example
all built-in images are stored in the library. The image is the re-created
from the string by first decoding the base64 data and then read in the data
with the GD function <code class="code">imagecreatefromstring()</code> .</p>
</div><p>
</p>
</div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"> </td><td width="20%" align="center"><a accesskey="u" href="ch13.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top"> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>