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copied!<p>The C language provides the function <strong>getopt</strong> to parse command-line options. The <strong>getopt_long</strong> function is a GNU extension that parses command-line options that offer more functionality than <strong>getopt</strong> such as multi-character options parsing. You can find documentation here : <a href="http://linux.die.net/man/3/getopt_long" rel="nofollow">http://linux.die.net/man/3/getopt_long</a> or simply a man <strong>getopt_long</strong>. Let me show an example. Let's say you have a program that have 3 options (-h for help message, -i for displaying an integer and -s for displaying a String). First, you must declare a <strong>struct options</strong>. This structure will contains all options that your program needs and is defined like this :</p> <pre><code> struct option { const char *name; // the option name int has_arg; // if your option has an argument - no_argument (equivalent to 0) if no option and required_argument otherwise (1) int *flag; // specifies how results are returned for a long option. If flag is NULL, then getopt_long() returns val int val; // is the value to return, or to load into the variable pointed to by flag. }; </code></pre> <p>As your program as many options, you must declare an array of struct options :</p> <pre><code>struct option options[] = { {"help", no_argument, NULL, 'h'}, // for the help msg {"int", 1, required_argument, 'i'}, // display an int {"string", required_argument, NULL, 's'}, // displays a string {NULL, 0, NULL, 0}}; </code></pre> <p>And you read your options as follow :</p> <pre><code> int main(int argc, char* argv[]){ char opt; while ((opt = getopt_long (argc, argv, "his:", options, NULL)) != -1) { switch(opt){ case 'h': printf("Help message \n"); exit(0); case 'i': printf("Int options = %d\n", optarg);break; case 's': printf("String option = %s\n", optarg); break; default: printf("Help message\n"); } } </code></pre> <p>Don't forget to include <strong>"getopt.h"</strong></p> <p>Good Luck</p>

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