www.digitalmars.com         C & C++   DMDScript  

c++ - how to solve "need explicit cast to convert"???

reply konst <kdiguine yandex.ru> writes:
hi, all!

I'm trying to compile yassl using dmc for dos real mode. everything
seems ok but i've got an error: "need explicit cast to convert" in the
following code ():

...
const Integer& Multiply(const Integer &a, const Integer &b) const
        {
            return result1 = a * b % modulus; // error is here!
        }
...
protected:
    Integer modulus;
    mutable Integer result, result1;
...

Integer is a class with lots of methods.
should I remove this "const" from all methods like "Multiply" or is
there another way?

thanx!
Oct 28 2008
parent Heinz Saathoff <newshsaat arcor.de> writes:
Hello,

konst wrote ...

 I'm trying to compile yassl using dmc for dos real mode. everything
 seems ok but i've got an error: "need explicit cast to convert" in the
 following code ():
 
 ...
 const Integer& Multiply(const Integer &a, const Integer &b) const
         {
             return result1 = a * b % modulus; // error is here!
         }
 ...
 protected:
     Integer modulus;
     mutable Integer result, result1;
 ...
 
 Integer is a class with lots of methods.
 should I remove this "const" from all methods like "Multiply" or is
 there another way?


Seems to be a bug in DMC. My PC-Lint and the borland C++ compile this 
example, but DMC does not:

   class Integer {
   public:
      Integer();
      Integer &  operator= (const Integer &rhs);
      friend Integer  operator* (const Integer &a, const Integer &b);
      friend Integer  operator% (const Integer &a, const Integer &b);
   };

   class MyInteger {
   public:
      const Integer& Multiply(const Integer &a, const Integer &b) const
           {
               return result1 = a * b % modulus; // error is here!             
       
           }
   protected:
       Integer modulus;
       mutable Integer result, result1;
   };

   int foo()
   {  MyInteger a, b, c;
      return 0;
   }

Maybe there is a problem with the handling of mutable here?


- Heinz
Oct 29 2008