Weird compiler error.

[JRevor]

I have two classes, Monomio (which represents a monom.. with its coefficient,and exponent) and Polinomio, which has a dynamic array of Monoms.

In Polinomio, i have declared this private function

unsigned Polinomio::max(const unsigned& a,const unsigned& b)
{
   if ( a > b){
      return  a;
   }
   else{
      return b;
   }         
}

im using it on some operator overloads which are within the class (For example, operator + and operator - ) like this :

bool Polinomio::operator==(const Polinomio& p) const 
{
   unsigned i = 0;
   bool output = true;
   unsigned tam = 0; //tam is the max size
   //calculates max exponent plus one. That is the size of the biggest polinom
   tam = max(this.at(length_-1).exp() +1,p.at(p.length()-1).exp()+1); // Something is wrong here
   //compares both polinoms, monom to monom
   while ((output==true)&&(i< tam)){
      cout << "i = " << i << endl;
      output = output&&( read(i) == p.read(i)); //Read(i) returns the monom
                                                //of exponent i in its polinom
      i++;
   }
   return output;
}

, i receive the following error:

In member function `bool Polinomio::operator==(const Polinomio&) const': `at' is not a type request for member of non-aggregate type before '(' token

if i remove this, then i receive passing `const Polinomio' as `this' argument of `unsigned int Polinomio::max(const unsigned int&, const unsigned int&)' discards qualifiers

this.at(length_-1).exp() +1 should return an unsigned

p.at(i), where p is a polinom, return the monom in the i position of the array (be careful, is different to read(i) , but at works properly : i've tested it already)

m.exp() ,where m is a monom, returns the exponent of the monom, which is an unsigned

What is going on here?

[Duthomhas]

this is a pointer. You need this->at(length_-1).
Hope this helps.

[JRevor]

Still doesn't work. (and i receive the second error : `const Polinomio' as `this' argument of `unsigned int Polinomio::max(const unsigned int&, const unsigned int&)' discards qualifiers )

[Bazzy]

If the operator == is const, you can call only const function from there

[JRevor]

Thanks Bazzy, that solved the problem.
To tell the truth, the error wasn't really self-explanatory.