Tokens, Keywords & Identifiers in C Programming Language

⇒ The C Declaration:-

• The programming language are designed to support certain kind of data such as numbers, characters, strings etc to get useful output known as result data consist of digits alphabets and symbols.
• A program should support these data type for getting the required output known as Information.
• A program is a set of statement which perform a specific task executed by user in a sequence form.
• These statement or instruction are formed using certain words and symbols according to the rules known as syntax rule or grammar of the language.
• Every program must accurately follow the syntax rule support by the language.

⇒ TOKENS:-

          The smallest unit in a program or statement is called a token.Tokens are classified in the following types -

• Keywords: Keywords are reserve word by the compiler. There are 32 keywords.
• Variables: These are user defined. Any numbers of variables can be defined.
• Constant: Constant are assigned to variable.
• Operators: Operators are different types and are used in different declaration in 'C'.
• String: A sequence of Characters.

⇒ KEYWORDS:-

    The C-keywords are reserved word by the compiler. All the C-keywords have been assigned fixed meaning and they cannot be used as variable names.It is suggested that the keywords shouldn’t be mixed up with variable name.For utilizing the keywords in a program no header file is required to be include.

         There are 32 keywords available in ANSI C

i.e. auto, break, case, char, const, continue, default, do, double, else, enum, extern, float, for, goto, if, int, long, resister, return, short, signed, sizeof, static, struct, switch, typedef, union, unsigned, void, volatile, while.

⇒ IDENTIFIERS:-

•  A symbolic name is use to refer to a variable, constant, function, structure, union etc.
• Identifiers are the name of variable, functions, arrays etc.
• They refer to a variety of entities such as structures, union, constant, functions, and objects.
• An identifier always starts with an alphabet and it’s a plane sequence of alphabets and/or digits.
• C-Identifiers doesn’t allow blank spaces punctuation and signs.
• Identifiers are user defined names. They are generally defined in lower case latter. However, the upper-case latter are also permitted.
• The underscore (_) symbol can be used as an identifier.
• Valid identifiers are: length, area, volume, sUM.
• Invalid identifiers are: length of line, s+um, year’s.