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Table of contents
Rules to Name an Identifier in C++:
Frequently Asked Questions
Are identifiers case-sensitive in C++?
Can I use special characters like @ or $ in identifiers?
What happens if I use a keyword as an identifier?
Last Updated: Jun 13, 2024

Identifiers in C++

Author Rahul Singh
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C++ is a popular programming language which is used by developers worldwide. While we write code in C++, we use identifiers to name variables, functions, classes, & other elements. Identifiers play a crucial role in making our code readable & understandable. 

Identifiers in C++

In this article, we will discuss what identifiers are, the rules for naming them, with some examples of valid & invalid identifiers in C++.

Rules to Name an Identifier in C++:

In C++, there are certain rules we need to follow when naming identifiers. These rules ensure that our code is consistent & follows the language standards. These rules are : 

  • Identifiers can only contain letters (a-z, A-Z), digits (0-9), & underscores (_). No other special characters are allowed.
  • Identifiers cannot start with a digit. They must begin with a letter or an underscore.
  • C++ is case-sensitive, which means uppercase & lowercase letters are considered different. For example, "myVariable" & "myvariable" are two different identifiers.
  • Keywords (reserved words) in C++ cannot be used as identifiers. For instance, you cannot use "int" or "for" as an identifier name.
  • Identifiers should be descriptive & meaningful. They should clearly indicate the purpose of the variable, function, or class they represent.
  • It is good practice to use camelCase or snake_case when naming identifiers. For example: "myVariableName" or "my_variable_name".
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Frequently Asked Questions

Are identifiers case-sensitive in C++?

Yes, identifiers in C++ are case-sensitive. This means that "myVariable" & "myvariable" are considered different identifiers.

Can I use special characters like @ or $ in identifiers?

No, identifiers in C++ can only contain letters, digits, & underscores. Special characters like @, $, or - are not allowed.

What happens if I use a keyword as an identifier?

Using a keyword as an identifier will result in a compilation error. Keywords are reserved words in C++ & cannot be used as identifiers.


In this article, we learned about identifiers in C++. We discussed the rules for naming identifiers, such as using only letters, digits, & underscores, starting with a letter or underscore, & avoiding keywords. We also saw examples of valid & invalid identifiers. By following these rules & conventions, we can write clean, readable, & maintainable code in C++.

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