Why is `const int& k = i; ++i; ` possible? [duplicate]

Question

I am supposed to determine whether this function is syntactically correct:

int f3(int i, int j) { const int& k=i; ++i; return k; }

I have tested it out and it compiles with my main function.

I do not understand why this is so.

Surely by calling the function f3 I create copies of the variables iand j in a new memory space and setting const int& k=i I am setting the memory space of the newly created k to the exact the same space of the memory space of the copied i, therefore any change, i.e. the increment ++iwill result in ++k which is not possible given that it was set const

Any help is greatly appreciated

Answer 1

the increment ++i will result in ++k which is not possible given that it was set const

That's a misunderstanding.

You may not change the value of the object through k but it can still be changed through other means. In other words, ++k is not allowed but ++i is still allowed, which will indirectly modify the value of k.

Here's an analogy from a non-computer world.

You may look through the window of a store and see what's inside but you won't be able to change what's inside the store. However, an employee, who is inside the store, can change the contents of the store. You will see that change from outside. You have const access or view access to the store while the employee has non-const access or change access to the store.