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| <h5 class="subsubsection">25.3.11.2 A Program Using Argp with Only Default Options</h5> |
| |
| <p>This program doesn't use any options or arguments, it uses argp to be |
| compliant with the GNU standard command line format. |
| |
| <p>In addition to giving no arguments and implementing a ‘<samp><span class="samp">--help</span></samp>’ |
| option, this example has a ‘<samp><span class="samp">--version</span></samp>’ option, which will put the |
| given documentation string and bug address in the ‘<samp><span class="samp">--help</span></samp>’ output, |
| as per GNU standards. |
| |
| <p>The variable <code>argp</code> contains the argument parser |
| specification. Adding fields to this structure is the way most |
| parameters are passed to <code>argp_parse</code>. The first three fields are |
| normally used, but they are not in this small program. There are also |
| two global variables that argp can use defined here, |
| <code>argp_program_version</code> and <code>argp_program_bug_address</code>. They |
| are considered global variables because they will almost always be |
| constant for a given program, even if they use different argument |
| parsers for various tasks. |
| |
| <pre class="smallexample"> /* <span class="roman">Argp example #2 -- a pretty minimal program using argp</span> */ |
| |
| /* <span class="roman">This program doesn't use any options or arguments, but uses |
| argp to be compliant with the GNU standard command line |
| format. |
| |
| In addition to making sure no arguments are given, and |
| implementing a --help option, this example will have a |
| --version option, and will put the given documentation string |
| and bug address in the --help output, as per GNU standards. |
| |
| The variable ARGP contains the argument parser specification; |
| adding fields to this structure is the way most parameters are |
| passed to argp_parse (the first three fields are usually used, |
| but not in this small program). There are also two global |
| variables that argp knows about defined here, |
| ARGP_PROGRAM_VERSION and ARGP_PROGRAM_BUG_ADDRESS (they are |
| global variables because they will almost always be constant |
| for a given program, even if it uses different argument |
| parsers for various tasks).</span> */ |
| |
| #include <argp.h> |
| |
| const char *argp_program_version = |
| "argp-ex2 1.0"; |
| const char *argp_program_bug_address = |
| "<bug-gnu-utils@gnu.org>"; |
| |
| /* <span class="roman">Program documentation.</span> */ |
| static char doc[] = |
| "Argp example #2 -- a pretty minimal program using argp"; |
| |
| /* <span class="roman">Our argument parser. The </span><code>options</code><span class="roman">, </span><code>parser</code><span class="roman">, and |
| </span><code>args_doc</code><span class="roman"> fields are zero because we have neither options or |
| arguments; </span><code>doc</code><span class="roman"> and </span><code>argp_program_bug_address</code><span class="roman"> will be |
| used in the output for ‘</span><samp><span class="samp">--help</span></samp><span class="roman">’, and the ‘</span><samp><span class="samp">--version</span></samp><span class="roman">’ |
| option will print out </span><code>argp_program_version</code><span class="roman">.</span> */ |
| static struct argp argp = { 0, 0, 0, doc }; |
| |
| int main (int argc, char **argv) |
| { |
| argp_parse (&argp, argc, argv, 0, 0, 0); |
| exit (0); |
| } |
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