Bigint Operations

[dudicus14]

Here I've got 2 classes, one is finished(a safeArray that I use for the second class which is what I have the problem with) In my bigint class I have add and subtract methods that work perfectly(i didnt include them below to save space.) But what I can't get to work is my multiplication method. The program compiles but doesnt return what I want. Any help would be greatly appreciated. Thanks

#include <iostream>
using namespace std;


template<typename Element>
class SafeArray
{
    int size;
    Element*Array;
    Element def;
    
public:
    SafeArray()                         //default constructor(with no parameter)
    {
                size = 10;
        Array = new Element[size];

        
    }
    SafeArray(int value)         //constructor with one int
    {
        size = value;
        Array = new Element[value];
       
    }
    ~SafeArray() {
        delete [] Array;
    }                                       //destructor
    Element get(int pos)                    //get method
        { if (pos<0)
        {cout<<"error";}
    
            if(pos>=size)
            { set_default(def);}
            return Array[pos]; }

    void set(int pos, Element val)
    {
        if (pos<0)
        {
            cout<<"error";
            return;
        }
        if(pos>=size)
        {
            resize(pos+1);
        }
        Array[pos] = val;
    }
    void resize(int new_size)
    {
        Element*temp=new Element[new_size];
        for(int i = 0; i<size;i++)
        {temp[i]=Array[i];}
        delete[]Array;
        Array = temp;
        size=new_size;
    }
    void set_default(Element d)        //set_default
    {
        def=d;
    }
        int get_size()                       //get size
    {
        return size;
    }
};

int size = 100;

class bigint
{
    SafeArray<int> *arr;
public:
    bool sign;
bigint()                                                   //initializes to zero
    {
        arr = new SafeArray<int>;
        for(int i =0;i < size; i++)
            arr->set(i,0);
    }
    
void print()                                               //prints numbers without zeroes in front
    {
        bool start_num=false;
        for(int i = 0;i <arr->get_size() ;i++)
        {
            if(arr->get(i)!=0 && start_num==false )
            {start_num=true;
                cout << arr->get(i);}
         else if(start_num==true)
             cout<<arr->get(i);
            
        }
        
       cout<<endl;
    }
    
void assign(const bigint &A)                             //
    {
        for(int i=0;i<arr->get_size();i++)
        {                                                            //Ways to initialize stuff
            arr->set(i,A.arr->get(i));
        }
    
    }
    
void assign(int num)                                     //
    {
        for(int i = arr->get_size()- 1; i >= 0; i--)
        {
            arr->set(i,num%10);
            num /=10;
        }
       
        
    }
    
void assign(string num)                                  //
    {
        long len = num.length();
        int j=arr->get_size()-1;
        for(long i=len-1;i>=0;i--)
        {
            arr->set(j,num[i]-48);
            j--;
        }
    }
void multiply(const bigint &A)
    {
        bigint temp1; // bigint with value 0
        
        int carry = 0;
        int shift = 0;
         bigint temp2;
        for(int j = size-1; j >= 0; j--) //no member size in bigint
        {
            for(int i=size-1; i>=0; i--)
            {
                // bigint with value 0 and size: size + A.size
                int result = (arr->get(i)*A.arr->get(j)+carry);
                
                if(size - shift - (i - size-1) >= 0)
                    temp2.arr->set(size - shift - (i - size-1), result%10);
                else
                    break;

                carry=result/10;
            }
            shift++;
            temp1.add_pos(temp2);
        }
        this->assign(temp1);
    }


int main()
{
 bigint a,b;
a.assign("1234");
b.assign("5678");
a.multiply(b);
a.print();

return 0;
}

[cire]

On line 131, you are not beginning with the value 0. A newly created bigint variable has unspecified values stored in this->arr.

Why is arr a pointer? Why is the def member of SafeArray never used outside of set_default? Why do the constructors not set it to some reasonable value?