Keywords and Identifiers in C

Each of the C program is a collection of instructions and even every instruction is a collection of some individual units. These individual smallest unit is known as tokens. Every instruction in a c program is a collection of tokens and they are the basic building blocks of any c program.

In a C program token may contain the following:

• Keywords
• Identifies
• Operators
• Special symbols
• Constant
• String
• Data values

In a C program, collection of all keywords, identifiers, operators, special symbols, constants, string , and data values are called tokens.

Keywords:

• Keywords are like reserve word in c with a predefined meaning which is already known to the compiler.
• There are total 32 keywords in C.
• They are also known as reserved words.

Properties of Keywords:

• All the keywords in C programming language are defined as lowercase letter.
• They cannot be used for naming a variable, function, array , pointer etc.
• Some predefined function associated with each keywords and this cannot be modified.

Keyword in C:

Identifiers:

• Identifiers are name given to variables, constant, functions and user-defined data such as array, pointer, structure, etc.
• In other words it can be defined as the user-defined name to identify an entity uniquely in the C programming language.

These identifiers must follow certain rules, those are as follows:

• An identifier can only have alphanumeric characters(a-z, A-Z, 0-9) and underscore(_).
• The first character of an identifier can only contain alphabet(a-z, A-Z) or underscore (_).
• They are case-sensitive that is “name” and “Name” are two different identifiers.
• No special characters, such as a semicolon, period, whitespaces, slash, or comma are permitted to be used in or as an Identifier.

Example:

int var;
here “int” is a keyword and “var” is an identifier.

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‹ Constant in C

Declaration, definition and initialization of variable and function ›

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Categories: C Language