(Solved Homework): Identify the three hard rules for user-defined identifiers. If a programmer breaks these rules, then the compiler will rep…

An identifier is a string of alphanumeric characters that begins with an alphabetic character or an underscore character that are used to represent various programming elements such as variables, functions, arrays, structures, unions and so on. Actually, an identifier is a user-defined word.

Difference Between Keyword and Identifier. Every language has keywords andidentifiers, which are only understood by its compiler. Keywords are predefined reserved words, which possess special meaning. … An identifier is a unique name given to a particular variable, function or label of class in the program.

Keywords are part of the syntax and they cannot be used as an identifier. For example: int money; Here, int is a keyword that indicates ‘money’ is a variable of type integer. As C is a case sensitive language, allkeywords must be written in lowercase.

Rules for User defined Identifiers:

• Identfiers can contain capital letters, smal letters and numbers.

car, anObject, myProGram123, bga45WD

• The Identifiers need not be meaningful.
• Identifiers can contain inly the special characters _ and $.
• Identifiers should not start with a number and spaces.

SyntaxError: Unexpected number

• Keyword cannot be used as identifiers.

SyntaxError: package is a reserved identifier

SyntaxError: Unexpected reserved word 

• Identifiers are case sensitive

Definition – What does Software Program mean?

In computer science and software engineering, computer software is all information processed by computer systems, programs and data. Computer software includes computer programs, libraries and related non-executable data, such as online documentation or digital media.

or

A software program is commonly defined as a set of instructions, or a set of modules or procedures, that allow for a certain type of computer operation. The term is also often used interchangeably with terms like “software application” and “software product.”

Example: Internet browser, Music Player, Operating System.