Re: argv[] comparison

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Tue, 22 May 2007 16:56:05 +0200
Message-ID:
<5bgekaF2smh1kU1@mid.individual.net>
* Juha Nieminen:

Alf P. Steinbach wrote:

  #include <iostream>

  #include <cstddef>
  #include <string>
  #include <vector>
  #include <stdexcept>

  typedef std::vector<std::string> StringVector;

  bool throwX( char const s[] ) { throw std::runtime_error( s ); }

  void cppMain( StringVector const& arguments )
  {
      arguments.size() > 1
          || throwX( "usage: myprog ARG1" );

      if( arguments.at(1) == "NKDT" )
      {
          // Do something.
      }
      else
      {
          // Do something else.
      }
  }

  int main( int n, char* a[] )
  {
      try
      {
          cppMain( StringVector( a, a+n ) );
          return EXIT_SUCCESS;
      }
      catch( std::exception const& x )
      {
          std::cerr << "!" << x.what() << std::endl;
          return EXIT_FAILURE;
      }
  }


  Why such a complicated solution to such a simple problem? How about
simply:

int main(int argc, char* argv[])
{
    std::vector<std::string> cmdLine(argv, argv+argc);

    if(cmdLine.size() > 1 && cmdLine[1] == "NKDT")
    {
        // Do something
    }
    else
    {
        // Do something else
    }
}


Yours is not reusable without changes. Note that the code you put in
'main' is the code in 'cppMain' (and all code that is program-specific,
i.e. that has to be written), except that 'cppMain' is safer because it
doesn't give access to the C-style arguments and because it can safely
throw exceptions. Always think about reusing code instead of inventing
the wheel over and over with just slight details different.

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