embedaddon/confuse/doc/tutorial-html/ar01s02.html - view

File: [ELWIX - Embedded LightWeight unIX -] / embedaddon / confuse / doc / tutorial-html / ar01s02.html
Revision 1.1.1.2 (vendor branch): download - view: text, annotated - select for diffs - revision graph
Wed Mar 17 00:49:17 2021 UTC (3 years, 3 months ago) by misho
Branches: confuse, MAIN
CVS tags: v3_3, HEAD

confuse 3.3

1: <?xml version="1.0" encoding="UTF-8" standalone="no"?> 2: <!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>2. Other types of options</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="index.html" title="libConfuse tutorial" /><link rel="next" href="ar01s03.html" title="3. Introducing lists" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2. Other types of options</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="index.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s03.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="idm36"></a>2. Other types of options</h2></div></div></div><p> 3: Of course, not only strings can be specified in the configuration file. 4: libConfuse can parse strings, integers, booleans and floating point values. 5: These are the fundamental values, and they are all also available as lists. 6: We'll talk more about lists in the next chapter. 7: </p><p> 8: The macros used to initialize a string, integer, boolean and a 9: float is, respectively, <code class="function">CFG_STR()</code>, 10: <code class="function">CFG_INT()</code>, <code class="function">CFG_BOOL()</code>, 11: <code class="function">CFG_FLOAT()</code> and 12: <code class="function">CFG_PTR()</code>. All macros take three parameters: 13: the name of the option, a default value and flags. To retrieve the 14: values, use <code class="function">cfg_getstr()</code>, 15: <code class="function">cfg_getint()</code>, 16: <code class="function">cfg_getbool()</code>, 17: <code class="function">cfg_getfloat()</code> or 18: <code class="function">cfg_getptr()</code>, respectively. 19: </p><p> 20: Let's introduce an integer option that tells us how many times to print the 21: greeting: 22: </p><a id="listing3"></a><pre class="programlisting"> 23: 1 #include <stdio.h> 24: 2 #include <confuse.h> 25: 3 26: 4 int main(void) 27: 5 { 28: 6 cfg_opt_t opts[] = 29: 7 { 30: 8 CFG_STR("target", "World", CFGF_NONE), 31: 9 CFG_INT("repeat", 1, CFGF_NONE), 32: 10 CFG_END() 33: 11 }; 34: 12 cfg_t *cfg; 35: 13 int repeat; 36: 14 37: 15 cfg = cfg_init(opts, CFGF_NONE); 38: 16 if(cfg_parse(cfg, "hello.conf") == CFG_PARSE_ERROR) 39: 17 return 1; 40: 18 41: 19 repeat = cfg_getint(cfg, "repeat"); 42: 20 while(repeat--) 43: 21 printf("Hello, %s!\n", cfg_getstr(cfg, "target")); 44: 22 45: 23 cfg_free(cfg); 46: 24 return 0; 47: 25 } 48: 26 49: </pre><p> 50: Here we have used the <code class="function">CFG_INT()</code> macro to 51: initialize an integer option named "repeat". The default value is 1 52: as in the standard greeting. The value is retrieved with 53: <code class="function">cfg_getint()</code>. 54: </p><p><a id="negative-repeat-problem"></a> 55: But, wait a moment, what if the user specified a negative value for 56: "repeat"? Or a too large positive value? libConfuse can handle 57: that with a so-called validating callback. We'll come back to this 58: problem later on, but we will first take a look at lists. 59: </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="index.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ar01s03.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">libConfuse tutorial </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 3. Introducing lists</td></tr></table></div></body></html>