C++

13.10    “const”

The const keyword should not be underestimated in C++. When used correctly, it can be very useful to programmers. With it, the compiler can help avoid careless mistakes and discover design problems.

In C++, you can use const in various places: whether passed as a parameter, as a local variable, or as a data field of a class. Here is a (not exhaustive) explanation of what is declared as “immutable” by a const:

• static const int MAX = 100;Together with static, a constant is defined.

• const string& getName();The return value must not be changed.

• void print(const string& msg);The parameter is not changed within the function.

• void Widget::drawYourself() const;The method does not change its object.

The last item has a special ...