1.12. Identifiers, Types, and Literals

Identifiers are names that are used in C++ programs for functions, parameters, variables, constants, classes, and types.

An identifier consists of a sequence of letters, digits, and underscores that does not begin with a digit. An identifier cannot be a reserved keyword. See Appendix A, “C++ Reserved Keywords,” for a list of them. The standard does not specify a limit to the length of an identifier, but certain implementations of C++ examine only the first 31 characters to distinguish between identifiers.