C++ Identifiers

An identifier in C++ is a name given to a variable, function, class, or any other user-defined item. Identifiers are used to identify and refer to specific items in a C++ program. In this article, we will discuss the rules and guidelines for naming identifiers in C++.

Rules for Identifiers

In C++, identifiers must follow a set of rules to be considered valid:

  • Identifiers must begin with a letter or an underscore (_).
  • After the first character, identifiers can contain letters, digits, and underscores.
  • C++ is case-sensitive, so myVariable and myvariable are considered different identifiers.
  • Identifiers cannot be a keyword or a pre-defined identifier already used by the C++ language.
  • Identifiers can be of any length, but it’s best to keep them short and meaningful.

For example, myVariable, _private, and counter1 are all valid identifiers, while 1counter and for are not.

Best Practices for Identifiers

When naming identifiers in C++, it’s best to follow a few best practices to ensure that your code is readable and maintainable:

  • Use meaningful and descriptive names that clearly indicate the purpose of the identifier.
  • Use camel case notation, where the first letter of each word is capitalized, for variable and function names, e.g. myVariable.
  • Use snake case notation, where words are separated by an underscore, for constants and pre-processor macros, e.g. MAX_SIZE.
  • Use uppercase letters for constants and pre-processor macros, to make them easily distinguishable from variables and functions.
  • Keep identifiers short and simple, to make them easier to read and understand.

For example, instead of using a variable named a, it would be more meaningful to use a variable named age if it’s used to store a person’s age.


In this article, we have discussed the rules and best practices for naming identifiers in C++. Following these guidelines will help make your code more readable, maintainable, and less prone to errors. Remember to use meaningful and descriptive names, follow the appropriate naming conventions, and keep identifiers short and simple.

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