Kotlin Expression and Statement


In programming, expressions and statements are two fundamental concepts.

  • An expression is a combination of one or more values, operators, and/or function calls that returns a value. Expressions can be simple or complex, and they can include literals, variables, and other constructs.

For example, x + y is an expression that adds the values of x and y and returns the result.

  • A statement is a single line or block of code that performs a specific task, such as assigning a value to a variable, calling a function, or looping through a collection of items. Statements can contain one or more expressions.

For example, the following is a statement that assigns the value of 10 to the variable x:

val x = 10

Here's another example of a statement that uses an expression:

fun main() {
    val x = 10
    val y = 20
    val z = x + y // expression
    println("The sum of $x and $y is $z") // statement

In this program, the expression x + y calculates the sum of x and y, and the statement println("The sum of $x and $y is $z") prints a message to the console that includes the value of x, y, and z.

In Kotlin, every statement is also an expression. This means that a statement can return a value, and that value can be used as part of a larger expression or statement. For example, the following program uses a conditional expression to calculate the absolute value of a number:

fun main() {
    val x = -10
    val absX = if (x < 0) -x else x // conditional expression
    println("The absolute value of $x is $absX") // statement

In this program, the conditional expression if (x < 0) -x else x calculates the absolute value of x, and the statement println("The absolute value of $x is $absX") prints the result to the console. Note that the if expression is a statement that returns a value, which is then assigned to the variable absX.