What is a valid c plus plus identifier?

Answer 1

In C++ we provide names for the entities we create, the variables, functions and types in our programs. These names, or identifiers, are required to conform to some simple rules.

An identifier must start with a letter and is comprised of a sequence of letters and digits. Somewhat surprisingly, in this context the underscore _ is considered to be a letter (although there are conditions associated with its use). There's no restriction on the length of an identifier.

Answer 2

An identifier is a sequence of characters used to denote one of the following:

- object or variable name

- class, structure, or union name

- enumerated type name

- member of a class, structure, union, or enumeration

- function or class-member function

- typedef name

- label name

- macro name

- macro parameter

So, essentially, any time that you need to name any type of data object or function entity, the name is the identifier.

Answer 3

All legal identifiers in C++ must begin with a letter or underscore and must not clash with any reserved word other than override and final (both of which are contextual keywords). To avoid name clashes with existing identifiers, always use namespaces. A class is also a namespace, hence two classes can have the same member identifiers serving different purposes.

Answer 4

C++ identifiers follow the C convention: all identifiers must be composed of letters, digits and underscores, but cannot begin with a digit. By convention, variable identifiers are all lower case, user-defined data type identifiers have a leading capital and macro names are all uppercase. Breaking with the convention does not invalidate code, however the convention does make it much easier to differentiate what a name represents. All standard library data types are all lowercase, thus std::string is a standard library data type while String is a user-defined data type.

In addition, identifiers composed of two or more words are best separated with underscores. Programmers with a background in Pascal programming will often use "camel type" identifiers such as NameAndAddress, however a C-style name_and_addressidentifier is easier to read.

Answer 5

any character in [A-Z,a-z,_] optionally followed by a sequence of any character in [0-9,A-Z,a-z,_]

Answer 6

examples: i, j, k, L12, nCount, user_control

Answer 7

those which starts with _ (underscore), a-z, or A-Z

it cannot start with numbers

it cannot use reserve words

Answer 8

None of the above. :-)