Identifiers in C Language

Introduction to C Language Identifiers

An identifier is a name given to a program element such as a variable, function, array, or constant. Think of it as a label that allows programmers to refer to these elements in their code. Identifiers play a pivotal role in making code readable and understandable, and their appropriate usage enhances collaboration among developers.

int studentAge;
studentAge = 20;


  • The first line declares an identifier named studentAge of type int, which indicates that it will store integer values. This identifier is used to represent the age of a student.
  • The second line assigns the value 20 to the studentAge identifier. This means that the identifier now holds the value 20, representing the age of a student.

User-Defined Identifiers

Programmers can create their own identifiers for variables, functions, and arrays.

1. User-Defined Variable Identifier:

float circleRadius;


In this example, we've declared a user-defined variable identifier named circleRadius. This identifier is of type float, which means it will store floating-point (decimal) values. It could be used to represent the radius of a circle, for instance.

2. User-Defined Function Identifier:

int calculateSum(int a, int b) {
    return a + b;


Here, we've declared a user-defined function identifier named calculateSum. This function takes two integer parameters (a and b) and returns their sum. The identifier calculateSum is now associated with this function, allowing us to call it elsewhere in the code to perform the specified calculation.

3. User-Defined Array Identifier:

int scores[5];


In this example, we've declared a user-defined array identifier named scores. This array can hold 5 integer values, creating a collection of integers. The identifier scores is used to refer to this array, making it possible to access and manipulate its individual elements using indexing (e.g., scores[0]scores[1], etc.).

Identifier Length and Limitations

Identifiers must not exceed a certain length to ensure code readability and prevent errors.

Rules for Naming Identifiers

To maintain consistency and avoid errors, C language identifiers must adhere to certain rules:

  • They can only consist of letters (both uppercase and lowercase), digits, and underscores.
  • Identifiers must begin with a letter (uppercase or lowercase) or an underscore.
  • C is case-sensitive, so identifiers with different letter cases are treated as distinct.
  • Identifiers should not be C keywords, which are reserved for specific language features.
  • No special characters or spaces are allowed in identifiers.


In the intricate landscape of C programming, identifiers stand as the bridge between human understanding and machine execution. They facilitate effective communication within code and play a crucial role in the creation of reliable and maintainable software. By mastering the art of naming and using identifiers, programmers unlock the true potential of the C language.


1. What is an identifier in C language?

An identifier in C is a name used to identify various program elements, such as variables, functions, arrays, and more. It is essentially a user-defined name for a program entity.

3. Are there any reserved words that cannot be used as identifiers in C?

Yes, C has a set of reserved words (also known as keywords) that have special meanings and cannot be used as identifiers. Examples of reserved words include intifforwhile, and return.

4. Can I use special characters in identifiers in C?

No, special characters like @, #, $, and % are not allowed in C identifiers. Only letters, digits, and underscores are permitted.

5. Is it a good practice to use long and descriptive identifiers in C?

Yes, it is generally good practice to use meaningful and descriptive identifiers in C. This makes your code more readable and helps others understand the purpose of variables, functions, and other program elements.

6. Can an identifier start with a digit in C?

No, an identifier cannot start with a digit in C. It must begin with a letter or an underscore.