Скачать или смотреть Variables, Assignment & Data Types

Concepts
Variable
Assignment
Some Data Types in C++

From Standard for Programming Language C++
A declaration introduces names into a translation unit or redeclares names introduced by previous declarations. A declaration specifies the interpretation and attributes of these names.
A declaration is a definition unless it declares a function without specifying the function's body, it contains the extern specifier or a linkage-specification and neither an initializer nor a function-body, it declares a static data member in a class definition, it is a class name declaration, it is an opaque-enum-declaration, or it is a typedef declaration, a using-declaration, or a using-directive