What's wrong with const is that many programmers don't seem to be able to understand it completely, and a "half-const-correct" project simply does not work. This is what you need to know:

1. Foo vs. const Foo (or Foo const)
2. Foo& vs. const Foo& (or Foo const&)

• references-to-const bind to all kinds of things, while references-to-non-const don't

3. Foo* vs. const Foo* (or Foo const*)

• pointer variables can also be Foo* const and const Foo* const (or Foo const* const)

4. void Foo::mutator() vs. void int Foo::accessor() const

• but pointer members inside const member functions still point to non-const objects
• so we can accidentally return non-const data from a const-function

5. iterator vs. const_iterator

• iterator variables can also be const iterator and const const_iterator

Migrating to C++ from a language that has no const concept is quite hard, any many fail to see the point.

What's wrong with const is that many programmers don't seem to be able to understand it completely, and a "half-const-correct" project simply does not work. This is what you need to know:

1. Foo vs. const Foo (or Foo const)
2. Foo& vs. const Foo& (or Foo const&)

• references-to-const bind to all kinds of things, while references-to-non-const don't

3. Foo* vs. const Foo* (or Foo const*)

• pointer variables can also be Foo* const and const Foo* const (or Foo const* const)

4. void Foo::mutator() vs. int Foo::accessor() const

• but pointer members inside const member functions still point to non-const objects
• so we can accidentally return non-const data from a const-function

5. iterator vs. const_iterator

• iterator variables can also be const iterator and const const_iterator

Migrating to C++ from a language that has no const concept is quite hard, any many fail to see the point.

What's wrong with const is that many programmers don't seem to be able to understand it completely, and a "half-const-correct" project simply does not work. This is what you need to know:

1. Objects can be const
2. References to objects can be const

• references-to-const bind to all kinds of things, while normal references don't

3. Pointers can be const

• with pointer variables, we have four possible combinations of const before and after the star

4. Member functions can be const (this I find quite useful)

• but pointer members inside const member functions still point to non-const objects
• so we can accidentally return non-const data from a const-function

5. If you have a constant view on a container, begin and end silently yield a const_iterator

• not to be confused with a const iterator

Migrating to C++ from a language that has const concept is quite hard, any many fail to see the point.

What's wrong with const is that many programmers don't seem to be able to understand it completely, and a "half-const-correct" project simply does not work. This is what you need to know:

1. Foo vs. const Foo (or Foo const)
2. Foo& vs. const Foo& (or Foo const&)

• references-to-const bind to all kinds of things, while references-to-non-const don't

3. Foo* vs. const Foo* (or Foo const*)

• pointer variables can also be Foo* const and const Foo* const (or Foo const* const)

4. void Foo::mutator() vs. void int Foo::accessor() const

• but pointer members inside const member functions still point to non-const objects
• so we can accidentally return non-const data from a const-function

5. iterator vs. const_iterator

• iterator variables can also be const iterator and const const_iterator

Migrating to C++ from a language that has no const concept is quite hard, any many fail to see the point.