How to access a data member of class A from a member function of class B?

[Curten]

Hi,

I'm a beginner and need help with the following:

I have defined a class A where a private data member is an array of structs;

private:
vector<a_struct> Data;

The values of the structs in the array are set by the constructor (by reading data from a file) when an object of class A is created. The values of 'Data' can be accessed by a 'getData' memberfunction.

The problem is that I want to access 'Data' from a memberfunction of another class B. How can I do that without creating a new object of class A everytime i call the memberfunction of class B?

Thanks for the help...

[Banfa]

Where are you instantiating class A?

[Curten]

As it is now, class A is instantiated in main, something like this:

main
{
ClassA objectA(filename); //Values of datamember 'Data' are set.
a_function();

other operations using objectA...

}

in the definition of a_function(), there is a call to another function "assignCharge". "assignCharge" sets the values of datamembers of
objectB of class B and here I want to use the values of 'Data' to control the values set to objectB.

This is perhaps not the best "software engineering", but I'm supposed to edit a program of approx. 10,000 lines made by another person so this is basically how it has to be done... =)

Again, thanks

[Banfa]

Well you need objectA to be in scope in the called functions. Ways of doing this are

1. Make objectA global
2. Pass a refernce to objectA down into the functions
3. Make objectA a static member of class B (it there is only ever 1 instance of objectA).
4. Make objectA a singleton class, if there is only every 1 instance of objectA. objectA is a static member of class A.

The over-riding theme of all these is that there is only a single instance of objectA at any 1 time.