Re: argv[] comparison

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Mon, 21 May 2007 20:39:14 +0200
Message-ID:
<5be7amF2spobsU1@mid.individual.net>
* kaferro@hotmail.com:

What is the safest way to make an argv[] comparison? The code below
works.

#include <iostream>
#include <string>

using namespace std;

int main(int argc, char *argv[])
{
    string test;

    if(argc>1)
    test = argv[1];

    if(test=="NKDT")
        cout << "\nComparison is true. Have program do something.\n";
    else
        cout << "\nComparison is false. Have program do something else.\n";

    return 0;
}


Do the following:

   #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;
       }
   }

--
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