Refection return in C++

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I cannot understand what the following function returns.

int * begin(){ //
  return &this->data[0];
}

Does this function return the address of a reference? I didn’t understand it very well.

c++ pointer reference

  • Give more context to the code. What is the type of this->data?

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2 answers

4

It returns a pointer, which is an address of some object. The operator & takes an address of the object instead of taking the object itself.

In this case returns the address of this, who has a great chance of being a pointer or reference. I wonder if the intention was not to return his own this.

There must be some confusion because the statement & indicates that something is a reference, but depending on the context the same symbol is the operator is something quite different, despite having a relationship.

Understand What is the difference between pointer and reference?.

2

Maybe there are other possibilities. But one of them is a pointer to the first element of the array data of the object of a class implementing the member function begin().

  • this refers to the pointer to the object whose function is called.
  • the operators -> and [] precede the operator &, then we go to them.
    • The associativity of these two operators is left to right.
    • In that case this->data is a pointer to the array data.
    • And this->data[0] is an integer. The first element of the array data.
  • finally the operator & returns the address of the integer this->data[0].

Note that in this case, this->data and &this->data[0] return the same value.

A possible implementation:

#include <iostream>

struct s {
  s() : data{1, 2, 3} {};
  int *begin() { return &this->data[0]; };
  int data[3];
};

int main() {
  s var;
  std::cout << *var.begin() << "\n";
}

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