Pass by value, reference, pointer
Three ways to hand a function an argument — each answers “can the function change my variable, and does it copy anything?” differently.
void byValue(Node n); // copies n. Changes inside don't touch the caller's copy.
void byRef(Node& n); // no copy. Changes inside DO affect the caller's variable.
void byConstRef(const Node& n); // no copy, can't modify - the default for big objects
void byPointer(Node* n); // no copy, can modify, can be nullptr (which & can't be)Default rule of thumb
- Small, cheap-to-copy types (
int,float,bool) → pass by value, don’t overthink it. - Big objects you’re only reading →
const&, skip the copy. - Need to modify the caller’s variable →
&(or*if “no value at all” is a valid case).