Identifier and Its Rules

What is an identifier?

Identifier:-

Identifier is the name of the basic programming elements.

Rules of an Identifier:-

While defining the identifier we must follow the below rules, or else it leads to compile time error.

    

               1. Identifier should only contain

                         a.Alphabets.[a-z] to [A-Z] 

                         b.Digits [0-9]

                         c.Special Character[ _ ,$]

Example:

         

        These are Identifier

2. Identifiers should not start with a digit. A digit can be used from the second character onwards.

Example:                                                                                                              

1stStudent--->This Syntax False

firstStudent--->This Syntax True

  3. Identifier should not contain special character, only '_' and '$'    

Example:                                                                   

No#Stuent--->This Syntax False

        No$Student--->This Syntax True       

         No_Student--->This Syntax True         

4. Identifiers should not contain space in the middle of words. If we want to provide a gap between words, they must be connected with '_'.                                                                        

                                        

Example:                                                                       

First name--->This Syntax false

First_name--->This Syntax  True

5. Keywords cannot be used as user identifiers because they are available throughout JVM directly

Example :

6. There is no limit to identifier length