Hi every one well i have this problem: Im creating a method for multiplying two different lists sorted in arrays example: MyList a [9,9,9,9] * MyList B[1,1,9]

the problem is that i was told not to convert to a large int and then multiply like this 9999*9 +9999*1+9999*9

Since the objective is to use array Lists i already figure out that i have to take the firs number of one of the array's multiply it by each number on the second list (array) and stored each individual result in a new array and then use the method AddList (that i already create).

there's no problem on doing the "for" or anything else my only question is :

How can i create as many arrays as number on the list b and rename them on the process this is my idea of the algorithm:

void MyLIST::mult (MyList a, MyList B)
{
int count;
    for ( int i = b.size ,i>0;i-- ) //in our case b.size=3 so it should create 3 new list
          {
             myList i = new myList(); // this is the problem!!!!!! can't rename like this.
               
             for(int j =b.size-1; j>0; j-- )
                   {
                       for(int y=a.size-1; y>0; y--) 
                         {
                      i[count ]= a[y]*b[j]; //multiplication not every case contemplated here
                         count++;//counter to fill the new array 
                        }
                   }
          }
}

this algorithm wont work is just an example;
so again does any one have an idea of how can create the lists and renamed them with out knowing a fix number for the array size????

thanks in advance.
and just to be clear this isn't a homework just personal hobbie and asking here was my last resource thank you.

To start with, you need to be more careful about capitalization. C++ is a case-sensitive language; MyList is not the same as MyLIST or myList . This alone could be the source of some of the errors.

Secondly, you don't want to rename an object to something else; you want to copy the object to another object. Talking of 'renaming' is likely to confuse everyone, since you cannot do that.

Now, the reason that the MyList i = new MyList(); doesn't work is because the new operator returns a pointer to a newly allocated object, whereas declaring the List the way you have creates a local object of type MyList - not a pointer. if you declare it as

myList * list = new myList();

you'd be on the right track.

Note, however, that you need to delete the allocated memory when you're done with it:

MyList* MyList::mult (MyList a, MyList B)
{
    int count;

    for ( int i = b.size; i>0; i-- ) //in our case b.size=3 so it should create 3 new list
    {
        MyList* list = new MyList();

        for(int j = b.size - 1; j>0; j-- )
        {
           for(int y = a.size - 1; y>0; y--) 
           {
                list[count]= a[y]*b[j]; //multiplication not every case contemplated here
                count++;//counter to fill the new array 
           }
        }
    }
    return list;
}

This still isn't complete, however, as you need to be able to allocate a MyList with a given list size, which means that the MyList() constructor has to get a size and allocate the appropriately sized array, and the destructor has to free it.

Ok
before anything else thank you for your quick answer. Since it was my first post in the community i wasn't sure how specific i should be with my code but now i get and i also get that what i was asking for can`t be done as i wanted too il try to figure out a better way.

THANK YOU and Happy X-mas Schoil-R-LEA and DaniWeb Community