6.3 Error handling

In case of a command line usage error, a CmdLineException is thrown.

CmdLineException is derived from std::exception.

It has the following member functions:

• error_t get_error_code() const
  returns the current error code. Return values of type error are unknown_option, invalid_argument, too_many_arguments or argument_expected.
• const string& get_option() const
  returns the command line option the error occurred with.
• const char * what() const
  constructs an error message from the error code and the command line option.

A complete example with exception handling looks like this:

#include <iostream>
#include <string>

#include "cmdline.h"

using namespace std;
using namespace cmdl; // defined in cmdline.h

void PrintHelp(){/* like above */}
void AddStringToList(const string& s){/* like above */}

int main(int argc, char *argv[])
{
   try
   {                                                                                                           
      CmdLine CL;
      int anInt; 

      CL.Init( --argc, ++argv ); // skip program name

      CL.Call( "-h", PrintHelp );
      CL.GetSingleValue( "-N", anInt );
      CL.Call( "-S", AddStringToList,  CmdLine::cmdMultipleArgs );

      CL.Done();
   }

   // of course you may also catch an "exception"
   catch (CmdLineException& e) 
   {
      cerr << "error message:  " << e.what() << endl
           << "error code:     " << e.get_error_code() << endl
           << "cmdline option: " << e.get_option() << endl;
   }
}