Search results
Results From The WOW.Com Content Network
// A class template to express an equality comparison interface. template < typename T > class equal_comparable {friend bool operator == (T const & a, T const & b) {return a. equal_to (b);} friend bool operator!= (T const & a, T const & b) {return! a. equal_to (b);}}; // Class value_type wants to have == and !=, so it derives from // equal_comparable with itself as argument (which is the CRTP ...
Example implementation of expression templates : An example implementation of expression templates looks like the following. A base class VecExpression represents any vector-valued expression. It is templated on the actual expression type E to be implemented, per the curiously recurring template pattern.
In C++, classes can be forward-declared if you only need to use the pointer-to-that-class type (since all object pointers are the same size, and this is what the compiler cares about). This is especially useful inside class definitions, e.g. if a class contains a member that is a pointer (or a reference) to another class.
The following is a declaration of the concept "equality_comparable" from the <concepts> header of a C++20 standard library. This concept is satisfied by any type T such that for lvalues a and b of type T, the expressions a==b and a!=b as well as the reverse b==a and b!=a compile, and their results are convertible to a type that satisfies the concept "boolean-testable":
While typename is now the preferred keyword, older source code may still use the class keyword instead (for example see the difference in source code examples between The Design and Evolution of C++ by Bjarne Stroustrup published in 1994 and the source code examples in The C++ Programming Language: Fourth Edition by Bjarne Stroustrup published ...
[1] For example, C++ is a multi-paradigm language including OOP; [2] however, it is less object-oriented than other languages such as Python [3] and Ruby. [ 4 ] Languages with object-oriented features
The g++ compiler implements the multiple inheritance of the classes B1 and B2 in class D using two virtual method tables, one for each base class. (There are other ways to implement multiple inheritance, but this is the most common.) This leads to the necessity for "pointer fixups", also called thunks, when casting. Consider the following C++ code:
A class in C++ is a user-defined type or data structure declared with any of the keywords class, struct or union (the first two are collectively referred to as non-union classes) that has data and functions (also called member variables and member functions) as its members whose access is governed by the three access specifiers private, protected or public.