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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>4. Using sections</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="ar01s03.html" title="3. Introducing lists" /><link rel="next" href="ar01s05.html" title="5. Parsing from internal buffers" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">4. Using sections</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s03.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s05.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="idm78"></a>4. Using sections</h2></div></div></div><p>
3: So far, we have only use a flat configuration file. libConfuse can also handle
4: sections to build a hierarchy of options. Sections can be used to group options
5: in logical blocks, and those blocks can (optionally) be specified multiple
6: times.
7: </p><p>
8: Sections are initialized with the <code class="function">CFG_SEC()</code> macro. It also takes three
9: parameters: the name of the option, an array of options allowed in the section
10: and flags.
11: </p><p>
12: We'll extend the, now rather complex, hello program so we can do other kinds of
13: greetings, not just "Hello". Each greeting will have its own settings for
14: targets and repeat.
15: </p><a id="listing5"></a><pre class="programlisting">
16: 1 #include <stdio.h>
17: 2 #include <confuse.h>
18: 3
19: 4 int main(void)
20: 5 {
21: 6 cfg_opt_t greet_opts[] =
22: 7 {
23: 8 CFG_STR_LIST("targets", "{World}", CFGF_NONE),
24: 9 CFG_INT("repeat", 1, CFGF_NONE),
25: 10 CFG_END()
26: 11 };
27: 12 cfg_opt_t opts[] =
28: 13 {
29: 14 CFG_SEC("greeting", greet_opts, CFGF_TITLE | CFGF_MULTI),
30: 15 CFG_END()
31: 16 };
32: 17 cfg_t *cfg, *cfg_greet;
33: 18 int repeat;
34: 19 int i, j;
35: 20
36: 21 cfg = cfg_init(opts, CFGF_NONE);
37: 22 if(cfg_parse(cfg, "hello.conf") == CFG_PARSE_ERROR)
38: 23 return 1;
39: 24
40: 25 for(j = 0; j < cfg_size(cfg, "greeting"); j++)
41: 26 {
42: 27 cfg_greet = cfg_getnsec(cfg, "greeting", j);
43: 28
44: 29 repeat = cfg_getint(cfg_greet, "repeat");
45: 30 while(repeat--)
46: 31 {
47: 32 printf("%s", cfg_title(cfg_greet));
48: 33 for(i = 0; i < cfg_size(cfg_greet, "targets"); i++)
49: 34 printf(", %s", cfg_getnstr(cfg_greet, "targets", i));
50: 35 printf("!\n");
51: 36 }
52: 37 }
53: 38
54: 39 cfg_free(cfg);
55: 40 return 0;
56: 41 }
57: 42
58: </pre><p>
59: We have renamed the option array from "opts" to "greet_opts", and introduced a
60: new "opts" array that only has one option: a "greeting" section.
61: The second parameter of the <code class="function">CFG_SEC()</code> macro
62: points to the old greeting options "targets" and "repeat".
63: </p><p>
64: We have also used a couple of flags to alter the behaviour of the
65: section: CFGF_TITLE means that a greeting section should have a
66: title and the CFGF_MULTI flag tells libConfuse that this section
67: may be specified multiple times in the configuration file. The
68: title of a section is retrieved with the
69: <code class="function">cfg_title()</code> function.
70: </p><p>
71: The outmost loop (with index j) now loops through all given
72: sections in the configuration file. We retrieve a section with a
73: <code class="function">cfg_getnsec()</code> call. The value returned is a
74: pointer to a cfg_t struct, the same type as returned by
75: <code class="function">cfg_init()</code>. Thus we can use the ordinary value
76: retrieval functions <code class="function">cfg_getstr()</code>,
77: <code class="function">cfg_getint()</code> and so on to retrieve values of
78: options inside the section.
79: </p><p>
80: Ok, so how does the configuration file look like for this setup?
81: </p><pre class="programlisting">
82: # this is the configuration file for the hello program
83:
84: greeting Hello
85: {
86: targets = {"Life", "Universe", "Everything"}
87: repeat = 1
88: }
89:
90: greeting Bye
91: {
92: targets = {Adams}
93: repeat = 1
94: }
95: </pre><p>
96: The program will loop through the sections in the order specified
97: in the configuration file. First it will find the "Hello" section.
98: It prints the title of the section, "Hello", retrieved with
99: <code class="function">cfg_title()</code>. Then the targets are printed just
100: as in the previous examples, but this time the values are retrieved
101: from the cfg_greet section. Next, the section titled "Bye" is
102: found, and the values are retrieved from that section.
103: </p><p>
104: When run, the program produces the following:
105: </p><pre class="programlisting">
106: $ ./listing5
107: Hello, Life, Universe, Everything!
108: Bye, Adams!
109: $
110: </pre></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s03.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ar01s05.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">3. Introducing lists </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 5. Parsing from internal buffers</td></tr></table></div></body></html>
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