Variables, Data Types in kotlin with example

In Kotlin, variables and data types are fundamental concepts that allow you to store and manipulate data. Here’s an overview of how to declare and use variables along with the common data types in Kotlin:

Variables in Kotlin

Kotlin has two main types of variables: val and var.

• val: Declares a read-only variable. Once assigned, its value cannot be changed (similar to final in Java).
• var: Declares a mutable variable. Its value can be changed.

Declaring Variables

val readOnly: String = "Hello, World!"  // Immutable variable
var mutable: Int = 42  // Mutable variable

Type Inference

Kotlin can automatically infer the type of the variable based on the assigned value, so you can omit the explicit type declaration.

val inferredReadOnly = "Hello, World!"  // Type is inferred as String
var inferredMutable = 42  // Type is inferred as Int

Common Data Types in Kotlin

1. Numbers
   • Int: 32-bit integer
   • Long: 64-bit integer
   • Short: 16-bit integer
   • Byte: 8-bit integer
   • Double: 64-bit floating-point number
   • Float: 32-bit floating-point number

val myInt: Int = 100
val myLong: Long = 10000000000L
val myShort: Short = 10
val myByte: Byte = 1
val myDouble: Double = 123.45
val myFloat: Float = 123.45F

Characters

• Char: Represents a single character

val myChar: Char = 'A'

Boolean

• Boolean: Represents a true/false value

val myBoolean: Boolean = true

Strings

• String: Represents a sequence of characters

val myString: String = "Kotlin"

Examples of Using Variables and Data Types

Here are some examples demonstrating variable declaration and initialization with different data types:

fun main() {
    // Immutable variables (val)
    val name: String = "Alice"
    val age: Int = 25
    val pi: Double = 3.14159
    val isStudent: Boolean = true
    val grade: Char = 'A'

    // Mutable variables (var)
    var count: Int = 0
    count += 1  // count is now 1

    // Type inference
    val city = "New York"  // Kotlin infers the type as String
    var temperature = 30.5  // Kotlin infers the type as Double

    // Printing values
    println("Name: $name")
    println("Age: $age")
    println("Pi: $pi")
    println("Is Student: $isStudent")
    println("Grade: $grade")
    println("Count: $count")
    println("City: $city")
    println("Temperature: $temperature")
}

Summary

• val: Immutable variable.
• var: Mutable variable.
• Kotlin supports various data types such as Int, Long, Short, Byte, Double, Float, Char, Boolean, and String.
• Type inference allows you to omit explicit type declarations.

Understanding these basics will help you get started with Kotlin and write more complex programs efficiently.