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Wed Mar 17 00:49:17 2021 UTC (3 years, 4 months ago) by misho
Branches: confuse, MAIN
CVS tags: v3_3, HEAD

confuse 3.3

<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>5. Parsing from internal buffers</title><link rel="stylesheet" type="text/css" href="tutorial.css" /><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /><link rel="home" href="index.html" title="libConfuse tutorial" /><link rel="up" href="index.html" title="libConfuse tutorial" /><link rel="prev" href="ar01s04.html" title="4. Using sections" /><link rel="next" href="ar01s06.html" title="6. Validating callback functions" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5. Parsing from internal buffers</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s04.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s06.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="idm100"></a>5. Parsing from internal buffers</h2></div></div></div><p> So far, we have only parsed configuration data from files. libConfuse can also parse buffers, or in-memory character strings. We will use this to fix a problem in the previous code. </p><p> The problem is that without a configuration file, the hello program will not print anything. We want it to at least print the standard greeting "Hello, World!" if no configuration file is available. </p><p> We can't have a default value for a section that can be specified multiple times (ie, a section with the CFGF_MULTI flag set). Instead we will parse a default configuration string if no section has been parsed: </p><a id="listing6"></a><pre class="programlisting"> 1 #include <stdio.h> 2 #include <confuse.h> 3 4 int main(void) 5 { 6 /* ... setup options ... */ 7 8 cfg = cfg_init(opts, CFGF_NONE); 9 cfg_parse(cfg, "hello.conf"); 10 11 if(cfg_size(cfg, "greeting") == 0) 12 { 13 cfg_parse_buf(cfg, "greeting Hello {}"); 14 } 15 16 /* ... print the greetings ... */ 17 } </pre><p> Only the changes from the previous code is shown here. We check if the size of the "greeting" section is zero (ie, no section has been defined). In that case we call <code class="function">cfg_parse_buf()</code> to parse a default in-memory string "greeting Hello {}". This string defines a greeting section with title Hello, but without any sub-options. This way we rely on the default values of the (sub-)options "targets" and "repeat". </p><p> When this program is run, it issues the well-known standard greeting "Hello, World!" if no configuration file is present. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s04.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ar01s06.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4. Using sections </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 6. Validating callback functions</td></tr></table></div></body></html>