Identifiers in C: Types of Identifiers

What is an Identifier?

An identifier is the name given to entities such as variables, functions, arrays, and structures in a C program.

Rules for Naming Identifiers

• Can contain letters, digits, and underscores only.
• Must begin with a letter or an underscore, not a digit.
• Cannot be a reserved keyword.
• Case-sensitive — count and Count are different identifiers.
• No spaces or special symbols allowed.

Types of Identifiers

• Variable identifiers — names given to variables, e.g. age, total_marks.
• Function identifiers — names given to functions, e.g. calculateSum().
• Array identifiers — names given to arrays, e.g. marks[10].
• Structure/Union identifiers — names given to user-defined types.
• Label identifiers — names used with goto statements.

int age = 21;
float total_marks = 89.5;