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Tue Jan 24 14:48:55 2017 UTC (7 years, 5 months ago) by misho
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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>3.&#160;Introducing lists</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="ar01s02.html" title="2.&#160;Other types of options" /><link rel="next" href="ar01s04.html" title="4.&#160;Using sections" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3.&#160;Introducing lists</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s02.html">Prev</a>&#160;</td><th width="60%" align="center">&#160;</th><td width="20%" align="right">&#160;<a accesskey="n" href="ar01s04.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="3.&#160;Introducing lists"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id401321"></a>3.&#160;Introducing lists</h2></div></div></div><p>
    4:             That was easy. Now let's extend the program a bit so we can greet more than one
    5:             "target". We'd like to be able to specify a list of targets to greet.
    6:         </p><p>
    7:             The list versions of the initialization macros are named
    8:             <code class="function">CFG_STR_LIST()</code>,
    9:             <code class="function">CFG_INT_LIST()</code>,
   10:             <code class="function">CFG_BOOL_LIST()</code> and
   11:             <code class="function">CFG_FLOAT_LIST()</code>. They take the same
   12:             parameters as the non-list versions, except the default value must
   13:             be a string surrounded by curly braces.
   14:         </p><p>
   15:             The modified program is shown below:
   16:         </p><a id="listing4"></a><pre class="programlisting">
   17: 1	#include &lt;stdio.h&gt;
   18: 2	#include &lt;confuse.h&gt;
   19: 3	
   20: 4	int main(void)
   21: 5	{
   22: 6	    cfg_opt_t 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_t *cfg;
   29: 13	    int repeat;
   30: 14	    int i;
   31: 15	
   32: 16	    cfg = cfg_init(opts, CFGF_NONE);
   33: 17	    if(cfg_parse(cfg, "hello.conf") == CFG_PARSE_ERROR)
   34: 18	        return 1;
   35: 19	
   36: 20	    repeat = cfg_getint(cfg, "repeat");
   37: 21	    while(repeat--)
   38: 22	    {
   39: 23	        printf("Hello");
   40: 24	        for(i = 0; i &lt; cfg_size(cfg, "targets"); i++)
   41: 25	            printf(", %s", cfg_getnstr(cfg, "targets", i));
   42: 26	        printf("!\n");
   43: 27	    }
   44: 28	
   45: 29	    cfg_free(cfg);
   46: 30	    return 0;
   47: 31	}
   48: 32	
   49: </pre><p>
   50:             Three things are a bit different here. First, the macro to
   51:             initialize the "targets" option is
   52:             <code class="function">CFG_STR_LIST()</code>. This tells libConfuse that
   53:             "targets" is a list of strings. Second, the default value in the
   54:             second parameter is surrounded by curly braces. This is needed to
   55:             indicate to libConfuse where the list of values ends.
   56:         </p><p>
   57:             The third change is in the printing of the greeting. First we print
   58:             the "Hello" string. Then we loop through all values found for the
   59:             "targets" option. The number of values is retrieved with the
   60:             <code class="function">cfg_size()</code> function. The string values are
   61:             then retrieved with <code class="function">cfg_getnstr()</code>, which is an
   62:             indexed version of <code class="function">cfg_getstr()</code>. In fact,
   63:             <code class="function">cfg_getstr()</code> is equivalent to
   64:             <code class="function">cfg_getnstr()</code> with an index of zero.
   65:         </p><p>
   66:             In the configuration file hello.conf, we can now specify a list of targets to
   67:             greet:
   68:         </p><pre class="programlisting">
   69: # this is the configuration file for the hello program
   70: 
   71: targets = {"Life", "Universe", "Everything"}
   72: repeat = 1
   73:         </pre><p>
   74:             The output of the hello program, run with the above configuration file, is:
   75:             "Hello, Life, Universe, Everything!"
   76:         </p><p>
   77:             Again, if no targets were configured, the greeting would have been the standard
   78:             "Hello, World!".
   79:         </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s02.html">Prev</a>&#160;</td><td width="20%" align="center">&#160;</td><td width="40%" align="right">&#160;<a accesskey="n" href="ar01s04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.&#160;Other types of options&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;4.&#160;Using sections</td></tr></table></div></body></html>
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