189. this Pointer

Question.3

A developer calls a member function on two different objects:

class Motor {
   int speed;
public:
   void setSpeed(int s) { speed = s; }
};

Motor m1, m2;
m1.setSpeed(50);
m2.setSpeed(100);

How does setSpeed know which object's speed to modify?

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The compiler generates separate functions for each object
The compiler passes a hidden this pointer as the first argument -- m1.setSpeed(50) becomes setSpeed(&m1, 50) internally; this->speed resolves to the correct object
Member variables are stored in a global table indexed by object ID
The function reads the stack frame to find the object

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