How to manipulate the object a pointer represents C++

Question

I am building a data structure and need to manipulate the object indicated by a pointer. The object indicated by the pointer is:

//in header file
struct treeNode{
    int value;
    treeNode* left;
    treeNode* right;
};

My current implementation only changes what the pointer is pointing to.

target->value = oneLarger->value

Target and oneLarger are defined:

void method(treeNode* target){
    treeNode* oneLarger = (tree node retrieved by another method)
    target->value = more->value
}

Is this possible to do via pass by reference or do I have to pass by value?

Answer 1

You can do: by Pointer, by Ref, by Copy

note that changes made in the byCopy function will get lost as soon as the function is done!

Those options look like:

//by Pointer
void method(treeNode* target) {

    treeNode* oneLarger = ...
    target->value = oneLarger->value;
}

//by Ref
// since that is a ref, you access the value using the dot(.)  and not the `->` operator
void method(treeNode& target) {

    treeNode* oneLarger = ...
    target.value = oneLarger->value;
}

//by Copy
// since that is a copy, you access the value using the dot(.)  and not the `->` operator
void method(treeNode target) {

    treeNode* oneLarger = ...
    target.value = oneLarger->value;
}