When diving into C++, one of the first things you'll encounter is the need to name variables and functions. While it might seem like a trivial task, naming is more than just picking something that sounds right—it’s about adhering to conventions that will make your code readable, maintainable, and error-free. In this blog, we'll explore the essential naming standards in C++ and how following these guidelines can set you on the path to becoming a more proficient programmer.
The Basics of Naming in C++
In C++, names are used to designate variables, functions, classes, and more. These names, known as identifiers, follow specific rules:
1. Valid Characters
Identifiers can be composed of:
- Letters (both uppercase and lowercase)
- Numbers
- The underscore character (
_)
However, C++ is case-sensitive—meaning myVariable and MyVariable are two distinct identifiers. While the underscore is valid, using it at the beginning of a name is generally discouraged. This is because the C++ compiler uses internal names that begin with one or two underscores followed by a capital letter. To avoid potential confusion with these system names, steer clear of starting your identifiers with an underscore.
2. Starting with a Letter or Underscore
The first character of your identifier must be a letter (a-z, A-Z) or an underscore (_). You cannot begin an identifier with a number. This rule ensures that your code is easily distinguishable and conforms to C++ syntax.
3. No Length Restrictions
One of the liberating aspects of C++ is that there are no restrictions on the length of an identifier. This allows you to create meaningful, descriptive names that make your code self-explanatory. However, be mindful of the practical implications—especially with global variables and functions. Some linkers only evaluate a set number of characters (e.g., the first 8 characters). Therefore, it's wise to make the beginning of your identifiers unique and significant.
4. Avoiding Keywords
C++ has a set of reserved words known as keywords (like int, return, class, etc.) that have special meaning in the language. These cannot be used as identifiers. Attempting to use a keyword as a variable name will result in a compilation error, so it's important to familiarize yourself with the full list of C++ keywords.
5. Examples of Valid and Invalid Names
Let's look at some examples to clarify these rules:
Valid Names:
myVariableCounter1student_name_totalAmount
Invalid Names:
-
1stVariable(starts with a number) -
int(a C++ keyword) -
total$amount(contains an invalid character,$) -
void(another C++ keyword)
Best Practices for Naming
Now that you understand the rules, let's talk about some best practices that can help you write cleaner and more professional C++ code.
1. Use Descriptive Names
While x, y, and z might be tempting for quick variables, using descriptive names like totalSum, userAge, or fileName makes your code much more understandable. Remember, you’re not just coding for the machine—you’re coding for yourself and others who might read your code in the future.
2. Stick to a Consistent Naming Convention
Consistency is key. Whether you choose camelCase, PascalCase, or snake_case, stick to one naming convention throughout your project. For instance:
-
camelCase:firstName,totalAmount -
PascalCase:FirstName,TotalAmount -
snake_case:first_name,total_amount
3. Avoid Ambiguous Abbreviations
While abbreviations can save time, they can also lead to confusion. Instead of amt, use amount. Instead of num, use number. Your future self and your collaborators will thank you.
4. Prefix Variables for Clarity (When Needed)
In some cases, prefixing variables with a type indicator or scope can be useful. For example:
-
intTotalSum(indicating an integer type) -
m_totalSum(wherem_indicates a member variable of a class)
However, overuse of prefixes can clutter your code, so use them judiciously.
Take away
Mastering the art of naming in C++ might seem like a small step, but it’s foundational to writing good code. By following these naming standards and best practices, you’ll not only avoid common pitfalls but also make your code more readable, maintainable, and professional. Happy coding!
meet me at github@eddiegulay
Top comments (2)
Everything you've said is true for like 99% of all programming languages. There's really nothing specific to C++.
Many projects use different case styles for different types of things, e.g., PascalCase for classes but camelCase for variables.
You forgot to mention is that certain patterns of identifier are reserved for use by C++ specifically. See here starting with "In Declarations."
You're absolutely righ, many of these naming conventions apply across various programming languages, not just C++. I appreciate your point about different case styles for different types of identifiers, as well as the importance of mentioning reserved identifier patterns in C++.
The link you provided Cpp Identifiers is incredibly helpful, and I’m sure it will be a valuable resource for me and others who read the post. 😎