C++ Const Usage Explanation

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It’s easier to understand if you rewrite that as the completely equivalent

// v───v───v───v───v───v───v───v───v───v───v───v─┬┐
//                                               ││
//  v──#1    v─#2             v──#3    v─#4      #5
   int const * const Method3(int const * const&) const;

then read it from right to left.

#5 says that the entire function declaration to the left is const, which implies that this is necessarily a member function rather than a free function.

#4 says that the pointer to the left is const (may not be changed to point to a different address).

#3 says that the int to the left is const (may not be changed to have a different value).

#2 says that the pointer to the left is const.

#1 says that the int to the left is const.

Putting it all together, you can read this as a const member function named Method3 that takes a reference to a const pointer to an int const (or a const int, if you prefer) and returns a const pointer to an int const (const int).

(N.b. #2 is entirely superfluous.)

More Related Contents:

  1. Why isn’t it legal to convert “pointer to pointer to non-const” to a “pointer to pointer to const”
  2. What is meant with “const” at end of function declaration? [duplicate]
  3. Purpose of returning by const value? [duplicate]
  4. Do rvalue references to const have any use?
  5. How is a variable at the same address producing 2 different values? [duplicate]
  6. int vs const int& [closed]
  7. What kind of optimization does const offer in C/C++?
  8. Deleting a pointer to const (T const*)
  9. Functions with const arguments and Overloading
  10. Top-level const doesn’t influence a function signature
  11. Why catch an exception as reference-to-const?
  12. Why does “extern const int n;” not work as expected?
  13. changing the value of const variable in C++ [duplicate]
  14. C/C++ changing the value of a const
  15. Why does C++ not have a const constructor?
  16. Calling a const function rather than its non-const version
  17. Why use a const member function?
  18. Easy rule to read complicated const declarations?
  19. What are top-level const qualifiers?
  20. What is a constant reference? (not a reference to a constant)
  21. How to avoid code duplication implementing const and non-const iterators?
  22. constexpr const vs constexpr variables?
  23. How to convert “pointer to pointer type” to const?
  24. C++: Why is const_cast evil?
  25. Mixing extern and const
  26. Same function with const and without – When and why?
  27. vector and const
  28. Duplicate const qualifier allowed in C but not in C++?
  29. How do I initialize a const data member?
  30. Is there const in C?

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