starting an app via "new"

[hollingsworthd]

I am using a C++ library to build a GUI app in C++. The lib requires me to start all of my code from an init() and free it all through a shutdown() which are called (respectively) from the constructor and destructor.

I could easily just instantiate a class of mine in init() which starts all of my code and listeners, e.g.:
MyApplicationStuff* appObj;
...
void init(){
MyApplicationStuff appObj = new MyApplicationStuff();
}

But this would place that object in the free store and most of the code executed from within that object (basically my entire app) utilizes automatic objects (stack-based).

My Question:
If my app were designed to utilize the stack, would calling 'new' to start up my app cause everything to be in the free-store... even my automatic/local variables?

[weaknessforcats]

Creating an object on the heap DOES NOT put evferything on the heap. What goes on the heap are the data members of the object. And that's all.

When you call a method, the local variables go on the stack. The location of the call local variables has nothing to do with the location of the object.

Only when you use "new" does data go on the heap.

[hollingsworthd]

Creating an object on the heap DOES NOT put evferything on the heap. What goes on the heap are the data members of the object. And that's all.

When you call a method, the local variables go on the stack. The location of the call local variables has nothing to do with the location of the object.

Only when you use "new" does data go on the heap.

Thanks for the reply. I think you answered my question, but I still am not positive...

Given "someObj" is a member contained by value by "anObj" which is a member contained by value by "appObj"... and appObj is instantiated with new, is someObj on the stack or heap? Is anObj on the stack or heap?

I think you meant that someObj would be on the stack (i.e. _not_ free-store) and that anObj would be on the heap. Is this right?

[weaknessforcats]

Look at what you said:

Given "someObj" is a member contained by value by "anObj" which is a member contained by value by "appObj"... and appObj is instantiated with new, is someObj on the stack or heap? Is anObj on the stack or heap?

This is how it is set up:
1) appObj is allocated on the heap.
2) appObj contains anObj -> so anObj is on the heap
3) an Obj contains someObj -> so someObj is on the heap

That is, everything is on the heap becuse appObj is on the heap.

However, this applies only to the DATA MEMBERS.

Member functions don't have heaps or stacks. They are just functions. When you call one of these functions, the local variables will be on the stack. It makes no difference where the object is located.

A variable is on the heap only when you use "new". So this member function

void appObj::AFunction()
{
char* data = new char[50];
}

has the array on the heap and the pointer data (a local variable) on the stack.