Array of objects where the size of an object depends on user input

[brimp]

In c++, I need to have arrays of 256 nodes where the number of references in the nodes of an array is not determined until run time. The number of references is passed in to the constructor of a node. How would I get an array of nodes with each node containing 2 references and other array of nodes with 4, 8, or 16 references in each node?

I could get the size of a node and multiply it by 256 to get the size to pass to malloc. Is this the best way to do this?

I would like to declare an array of nodes and specify the node's constructor parameters in the declaration but I don't see how to do this.

class node
{
public:
unsigned int id;
unsigned short ReferencesUsed;
reference *Reference;
node(unsigned int MaxReferences);
};
node::node(unsigned int MaxReferences)
{
ReferencesUsed = 0;
Reference = new reference [MaxReferences];
id = 0;
};

main
{
unsigned int MaxRefs = 2;
node n2 = node(MaxRefs) [256]; // this is what I want but is not valid
MaxRefs=16;
node n16 = node(MaxRefs) [256];
// other code
}

:confused:

[Banfa]

I think when declaring an array of objects you have no optiuon but to call the default constructor.

However you could simply have the default constructor create a node with no references and a member function to call to then set the number of references for the node

node n2[256];
 
for(int i=0; i<256; i++)
    n2.SetNumberOfReferences(2);
 

[/code]

[brimp]

If I declare an array of nodes before I know the size of each node in the array then how will the compiler know how many bytes should be allocated for the array?

[Banfa]

The class node is of fixed size (all classes are of fixed size), the compiler already knows how big it is, all you have to supply is supply the number of references which is used to dynamically allocate memory so this can be done after the node has been instanciated.

Of course you could use templates

template<int MaxReferences> class node
{
public:
    unsigned int id;
    unsigned short ReferencesUsed;
    reference Reference[MaxReferences];
    node();
};
node::node()
{
    ReferencesUsed = 0;
    id = 0;
};
 
int main()
{
    node<2> n2[256];
    node<16> n16[256];
    // other code
}