Scala Identifiers

11 Nov, 2021
In programming languages, Identifiers are used for identification purpose. In Scala, an identifier can be a class name, method name, variable name or an object name. For example :  
class GFG{
    var a: Int = 20
}
object Main {
    def main(args: Array[String]) {
        var ob = new GFG();
    }
}
In the above program we have 6 identifiers: 
GFG: Class name
a: Variable name
Main: Object name
main: Method name
args: Variable name
ob: Object name 
There are certain rules for defining a valid Scala identifier. These rules must be followed, otherwise we get a compile-time error.  
Scala identifiers are case-sensitive.
Scala does not allows you to use keyword as an identifier.
Reserved Words can’t be used as an identifier like $ etc.
Scala only allowed those identifiers which are created using below four types of identifiers.
There is no limit on the length of the identifier, but it is advisable to use an optimum length of 4 – 15 letters only.
Identifiers should not start with digits([0-9]). For example “123geeks” is a not a valid Scala identifier.
Example: 
Scala
// Scala program to demonstrate// Identifiers object Main{         // Main method    def main(args: Array[String])    {             // Valid Identifiers    var `name` = "Siya";    var _age = 20;    var Branch = "Computer Science";    println("Name:" +`name`);    println("Age:" +_age);    println("Branch:" +Branch);    }}
Output:  
Name:Siya
Age:20
Branch:Computer Science
In the above example, valid identifiers are:  
Main, main, args, `name`, _age, Branch, +
and keywords are: 
Object, def, var, println
 
Scala supports four types of identifiers: 
Alphanumeric Identifiers: These identifiers are those identifiers which start with a letter(capital or small letter) or an underscore and followed by letters, digits, or underscores.Example of valid alphanumeric identifiers: 
 _GFG, geeks123, _1_Gee_23, Geeks
Example of Invalid alphanumeric identifiers: 
123G, $Geeks, -geeks
Example: 
Scala
// Scala program to demonstrate// Alphanumeric Identifiers object Main{         // Main method    def main(args: Array[String])    {             // main, _name1, and Tuto_rial are    // valid alphanumeric identifiers    var _name1: String = "GeeksforGeeks"    var Tuto_rial: String = "Scala"         println(_name1);    println(Tuto_rial);    }}
Output: 
GeeksforGeeks
Scala
Operator Identifiers: These are those identifiers which contain one or more operator character like +, :, ?, ~, or # etc. Example of valid operator identifiers: 
 +, ++ 
Example: 
Scala
// Scala program to demonstrate// Operator Identifiers object Main{         // Main method    def main(args: Array[String])    {             // main, x, y, and sum are valid    // alphanumeric identifiers    var x:Int = 20;    var y:Int = 10;         // Here, + is a operator identifier    // which is used to add two values    var sum = x + y;    println("Display the result of + identifier:");    println(sum);    }}
Output: 
Display the result of + identifier:
30
Mixed Identifiers: These are those identifiers which contains alphanumeric identifiers followed by undersoce and an operator identifier. Example of valid mixed identifiers: 
 unary_+, sum_= 
Example: 
Scala
// Scala program to demonstrate// Mixed Identifiers object Main{         // Main method    def main(args: Array[String])    {             // num_+ is a valid mixed identifier    var num_+ = 20;    println("Display the result of mixed identifier:");    println(num_+);    }}
Output: 
Display the result of mixed identifier:
20
Literal Identifiers: These are those identifiers in which an arbitrary string enclosed with back ticks (`....`) . Example of valid mixed identifiers: 
`Geeks`, `name` 
Example: 
Scala
// Scala program to demonstrate// Literal Identifiers object Main{         // Main method    def main(args: Array[String])    {             // `name` and `age` are valid literal identifiers    var `name` = "Siya"    var `age` = 20    println("Name:" +`name`);    println("Age:" +`age`);    }}
Output: 
Name:Siya
Age:20
kapoorsagar226
abhishek0719kadiyan
simmytarika5
Scala
Scala-Basics
Scala
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
For Loop in Scala
Scala | map() method
Scala | flatMap Method
String concatenation in Scala
Scala | reduce() Function
Type Casting in Scala
Scala List filter() method with example
Scala Tutorial – Learn Scala with Step By Step Guide
Scala String substring() method with example
Enumeration in Scala