C++ Primer, Fifth Edition

2.2.3. Identifiers

Identifiers in C++ can be composed of letters, digits, and the underscore character. The language imposes no limit on name length. Identifiers must begin with either a letter or an underscore. Identifiers are case-sensitive; upper- and lowercase letters are distinct:

// defines four different int variablesint somename, someName, SomeName, SOMENAME;

The language reserves a set of names, listed in Tables 2.3 and Table 2.4, for its own use. These names may not be used as identifiers.

Table 2.3. C++ Keywords

Table 2.4. C++ Alternative Operator Names

The standard also reserves a set of names for use in the standard library. The ...