Command-line-option-parser

A command line option parser for C/C++ projects. An alternative to getopt() and getopt_long() by using of callback functions in the shape of classical function-pointers or as anonymous "lambda" functions in C.

Advantages:

• Avoiding of global variables like "optind" or "optarg".
• Using of a callback function for each option instead of (confusing huge) switch-case statements. (Avoiding of spaghetti-code.)
• Use of anonymous callback functions (lambda functions) possible. That means implementation of the function body directly in the option-list initializer possible.
• Object oriented flavor: Short option-name (if given), long option-name (if given) and help-text (if given) are bound together in a single object by a corresponding callback function.
• Avoiding of redundance: If you'll change a option name, so you have to do this on one place in your source-code only.
• Commands by mixed order of options and non-options are possible (see example e2).
• Scalable, if a serten kind of option-type won't used for your project just define the corresponding compiler-switch (CONFIG_CLOP_NO_...) in your Makefile respectively build-system to reduce memory, provided you'll link the source-code directly to your project rather than the shared-library.

If you intend to write your project in C++11 just take a look in the following link:

https://github.com/UlrichBecker/command_line_option_parser_cpp11

Excuses my Eric Allman coding-style and my bad English ;-)

Code-example

You can also find a practical example of using this module in this repository: https://github.com/UlrichBecker/ioctl4bash

Example for classical order: first options, second non-options,

#include <parse_opts.h>
#include <stdlib.h>

struct MY_DATA
{
  // My data which shall be modified by the options...
  // If you'll avoid global variables.
  bool verbose;
  //...
};

static int optOneOfMyCallbackFunction( struct BLOCK_FUNCTION_ARG_T* pArg )
{
   // Callback function for option '-o' and "--myoption"
   // Do something...
   return 0;
}

int main( int argc, char** ppArgv )
{
   struct OPTION_BLOCK_T blockList[] =
   {
      { // Using of classical function-pointer as callback function.
         .optFunction = optOneOfMyCallbackFunction,
         .hasArg      = NO_ARG,
         .shortOpt    = 'o',
         .longOpt     = "myoption",
         .helpText    = "bla bla bla :-)"
      },
      { // Using of anonymous callback function which can be implemented directly in the initializer.
         OPT_LAMBDA( pArg, { ((struct MY_DATA*)pArg->pUser)->verbose = true; return 0; }),
         .hasArg      = NO_ARG,
         .shortOpt    = 'v',
         .longOpt     = "verbose",
         .helpText    = "Be verbose"
      },
      // Further options...
      OPTION_BLOCKLIST_END_MARKER
   };

   struct MY_DATA myData = { .verbose = false; };

   int i = parseCommandLineOptions( argc, ppArgv, blockList, &myData );
   if( i < 0 )
      return EXIT_FAILURE;
   for(; i < argc; i++ )
   {
      printf( "Non option argument: %s\n", ppArgv[i] );
   }

   // Do something others...

   return EXIT_SUCCESS;
}

Example for mixed order:

#include <parse_opts.h>
#include <stdlib.h>

struct MY_DATA
{
  // My data which shall be modified by the options...
  // If you'll avoid global variables.
  bool verbose;
};

static int optOneOfMyCallbackFunction( struct BLOCK_FUNCTION_ARG_T* pArg )
{
   // Callback function for option '-o' and "--myoption"
   // Do something...
   return 0;
}

int main( int argc, char** ppArgv )
{
   int i;
   struct OPTION_BLOCK_T blockList[] =
   {
      { // Using of classical function-pointer as callback function.
         .optFunction = optOneOfMyCallbackFunction,
         .hasArg      = NO_ARG,
         .shortOpt    = 'o',
         .longOpt     = "myoption",
         .helpText    = "bla bla bla :-)"
      },
      { // Using of anonymous callback function which can be implemented directly in the initializer.
         OPT_LAMBDA( pArg, { ((struct MY_DATA*)pArg->pUser)->verbose = true; return 0; }),
         .hasArg      = NO_ARG,
         .shortOpt    = 'v',
         .longOpt     = "verbose",
         .helpText    = "Be verbose"
      },
      // Further options...
      OPTION_BLOCKLIST_END_MARKER
   };

   struct MY_DATA myData = { .verbose = false; };

   for( i = 1; i < argc; i++ )
   {
      i = parseCommandLineOptionsAt( i, argc, ppArgv, blockList, &myData );
      if( i < 0 )
         return EXIT_FAILURE;
      if( i < argc )
         printf( "Non option argument in ppArgv[%d]: \"%s\"\n", i, ppArgv[i] );
   }

   // Do something others...

   return EXIT_SUCCESS;
}