Re: code not working to the end

From:
Ian Collins <ian-news@hotmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 30 Jun 2011 11:16:38 +1200
Message-ID:
<971q3lFfpqU7@mid.individual.net>
On 06/30/11 11:03 AM, net user wrote:

hi,

Anything to improve for someone learning in the code below...


It would have been helpful to have posted the real code!

/* 1- Compute a n*2 value for 64 iterations */
/* 2- Maximum integer variable iterations for n*2 */
/* 3- Computer the number of iteration needed to reach the value in
question 1 */
int main()
try
{
         long double var_long_double = 1 ;
         long double var_long_double2 = 1 ;
         unsigned int var_integer = 1 ;
         unsigned int var_integer2 = 1 ;
         int i = 1 ;
         int nb = 1 ;


Declaring these where they are used is better style.

         // QUESTION 1
         while (i< 64)


A for loop would have been clearer.

         {
                 var_long_double *= 2 ;
                 i++ ;
         }
         cout<< "\n1- Value for 64 iteration : "<< var_long_double ;
         //QUESTION 2
         while (var_integer> 0)


A for loop would have been clearer.

         {
                 cout<< "\n"<< nb<< "\tvar_int : "<< var_integer ;


This outputs 2^(n-1)).

                 var_integer *= 2 ;
                 nb++ ;
                 if (var_integer> 0)
                         var_integer2 = var_integer ;
         }
         cout<< "\n\n2- Number as integer variable for "<< nb<< "
incrementations : "<< var_integer2 ;
         // QUESTION 3
         i = 1 ;
         while (var_long_double>= 0)


This will run for (almost) ever.

         {
                 var_long_double /= 2 ;


var_long_double will never become zero.

                 if (var_long_double>= 0)
                         var_long_double2 = var_long_double ;
                 else
                         break ;
                 i++ ;
         }
         cout<< "\n3-Number of maximum iteration for i as int "<< i
<<
"\n" ;
         cout<< "\n\n" ;
         system("pause") ;
         return 0 ;
}

catch (runtime_error e)


Catching exceptions by value is not a good idea, catch by const reference.

{
         cout<< e.what()<< '\n' ;
         keep_window_open("~") ;
}

catch(...)
{
         cout<< "Exiting\n" ;
         keep_window_open("~") ;
}

I am running this on a 64 bits computer using Windev.
Above the fact that I don't see the code above very reliable, I don't
understand why I get to -2 147 483 648 with an unsigned int variable.
 From my understanding it should be 4 294 967 295...


Where do you get that value?

--
Ian Collins

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