Identifiers in C

Identifiers play a crucial role in programming languages, Serving as names for various program elements such as variables, functions, and more. In this article, we will see what are identifiers in C, the rules for identifiers in C, etc.

Identifiers in C

What are Identifiers in C?

Identifiers in C are user defined names given to various program elements like variables, functions, arrays, etc. These names act as labels, allowing developers to reference and manipulate these elements within the code. It is essential to choose meaningful and descriptive identifiers to enhance code clarity and maintainability.

Rules for Identifiers in C

C programming follows a set of rule for naming identifiers, ensuring consistency and avoiding confusions. Some key rules for identifiers in C are given below-

Character Set

In C Identifiers can consist of letters(both upper case and lower case), digits, and underscore characters (_). but the identifiers cannot start with a digit.

Length of Identifiers in C

In C there is no strict limit on identifier length but it is a good practice to keep name reasionably sort and meaningful.

Case Sensitive

C language is case sentisitiv, meaning uppercase and lowercase letters are treated differently. for example ‘myVariable’ and ‘myvariable’ could be considered as distinct identifiers.

Reserved Keyword

We can not use reserved keywords (if, for, int, etc) as identifiers because these are reserved for specific purpose in the C language.

Example of Valid Identifiers in C

Scope and Lifetime of Identifiers in C

Identifers in C have scope and lifetime, determining where in the C code they can be accesed and for how long they remain valid.


Scope refers to the reason for the program where an identifier is visible and accessible. For example, variables declared inside a function have a local scope, while variables declared outside any function have a gloabal scope.


Lifetime defines the duration for which an identifier remains in existence during program execution. Local variables have a limited lifetime, tied to the function’s execution, while global variables persist throughout the program’s runtime.

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