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3: <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>4. Using sections</title><link rel="stylesheet" href="tutorial.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><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" title="4. Using sections"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id400837"></a>4. Using sections</h2></div></div></div><p>
4: So far, we have only use a flat configuration file. libConfuse can also handle
5: sections to build a hierarchy of options. Sections can be used to group options
6: in logical blocks, and those blocks can (optionally) be specified multiple
7: times.
8: </p><p>
9: Sections are initialized with the <code class="function">CFG_SEC()</code> macro. It also takes three
10: parameters: the name of the option, an array of options allowed in the section
11: and flags.
12: </p><p>
13: We'll extend the, now rather complex, hello program so we can do other kinds of
14: greetings, not just "Hello". Each greeting will have its own settings for
15: targets and repeat.
16: </p><a id="listing5"></a><pre class="programlisting">
17: 1 #include <stdio.h>
18: 2 #include <confuse.h>
19: 3
20: 4 int main(void)
21: 5 {
22: 6 cfg_opt_t greet_opts[] =
23: 7 {
24: 8 CFG_STR_LIST("targets", "{World}", CFGF_NONE),
25: 9 CFG_INT("repeat", 1, CFGF_NONE),
26: 10 CFG_END()
27: 11 };
28: 12 cfg_opt_t opts[] =
29: 13 {
30: 14 CFG_SEC("greeting", greet_opts, CFGF_TITLE | CFGF_MULTI),
31: 15 CFG_END()
32: 16 };
33: 17 cfg_t *cfg, *cfg_greet;
34: 18 int repeat;
35: 19 int i, j;
36: 20
37: 21 cfg = cfg_init(opts, CFGF_NONE);
38: 22 if(cfg_parse(cfg, "hello.conf") == CFG_PARSE_ERROR)
39: 23 return 1;
40: 24
41: 25 for(j = 0; j < cfg_size(cfg, "greeting"); j++)
42: 26 {
43: 27 cfg_greet = cfg_getnsec(cfg, "greeting", j);
44: 28
45: 29 repeat = cfg_getint(cfg_greet, "repeat");
46: 30 while(repeat--)
47: 31 {
48: 32 printf("%s", cfg_title(cfg_greet));
49: 33 for(i = 0; i < cfg_size(cfg_greet, "targets"); i++)
50: 34 printf(", %s", cfg_getnstr(cfg_greet, "targets", i));
51: 35 printf("!\n");
52: 36 }
53: 37 }
54: 38
55: 39 cfg_free(cfg);
56: 40 return 0;
57: 41 }
58: 42
59: </pre><p>
60: We have renamed the option array from "opts" to "greet_opts", and introduced a
61: new "opts" array that only has one option: a "greeting" section.
62: The second parameter of the <code class="function">CFG_SEC()</code> macro
63: points to the old greeting options "targets" and "repeat".
64: </p><p>
65: We have also used a couple of flags to alter the behaviour of the
66: section: CFGF_TITLE means that a greeting section should have a
67: title and the CFGF_MULTI flag tells libConfuse that this section
68: may be specified multiple times in the configuration file. The
69: title of a section is retrieved with the
70: <code class="function">cfg_title()</code> function.
71: </p><p>
72: The outmost loop (with index j) now loops through all given
73: sections in the configuration file. We retrieve a section with a
74: <code class="function">cfg_getnsec()</code> call. The value returned is a
75: pointer to a cfg_t struct, the same type as returned by
76: <code class="function">cfg_init()</code>. Thus we can use the ordinary value
77: retrieval functions <code class="function">cfg_getstr()</code>,
78: <code class="function">cfg_getint()</code> and so on to retrieve values of
79: options inside the section.
80: </p><p>
81: Ok, so how does the configuration file look like for this setup?
82: </p><pre class="programlisting">
83: # this is the configuration file for the hello program
84:
85: greeting Hello
86: {
87: targets = {"Life", "Universe", "Everything"}
88: repeat = 1
89: }
90:
91: greeting Bye
92: {
93: targets = {Adams}
94: repeat = 1
95: }
96: </pre><p>
97: The program will loop through the sections in the order specified
98: in the configuration file. First it will find the "Hello" section.
99: It prints the title of the section, "Hello", retrieved with
100: <code class="function">cfg_title()</code>. Then the targets are printed just
101: as in the previous exemples, but this time the values are retrieved
102: from the cfg_greet section. Next, the section titled "Bye" is
103: found, and the values are retrieved from that section.
104: </p><p>
105: When run, the program produces the following:
106: </p><pre class="programlisting">
107: $ ./listing5
108: Hello, Life, Universe, Everything!
109: Bye, Adams!
110: $
111: </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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