boost中的lexical_cast和numeric_cast

#include  " stdafx.h "

using   namespace  std;
using  boost::lexical_cast;
using  boost::bad_lexical_cast;
using  boost::numeric_cast;
using  boost::bad_numeric_cast;

template < class  T >
bool  IsValid( const   string &  num){
     bool  flag = true ;
     try {
        T temp = lexical_cast < T > (num);
    }
    
     catch  (CFileException *  e){
        flag = false ;
    }
     return  flag;
}

using  std::endl;

int  _tmain( int  argc, _TCHAR *  argv[])
{
     string  s = " 6.02e-2 " ;
     try {
    cout << lexical_cast < double > (s) << endl;
     // cout<<lexical_cast<int>(s)<<endl;
    } catch (bad_lexical_cast & e){
        cerr << e.what() << endl;
    }

     try {
         int  i = 32767 ;
         short  s = numeric_cast < short > (i);
        cout << s << endl;
        i ++ ;

        s = i; // 发生上溢
        cout << s << endl; // 输出-32768

        s = numeric_cast < short > (i); // 抛出异常
      
         int  n =- 3 ;
        unsigned  int  m = n; // 发生下溢
        cout << m << endl; // 输出4294967293

        m = numeric_cast < unsigned  int > (n); // 抛出异常
    }
     catch (bad_numeric_cast & e){
        cerr << e.what() << endl;
    }
    
     return   0 ;
}