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Returns and Jumps Kotlin has three structural jump expressions: return . By default returns from the nearest enclosing function or anonymous function . break . Terminates the nearest enclosing loop. continue . Proceeds to the next step of the nearest enclosing loop. All of these expressions can be used as part of larger expressions: val s = person.name ?: return The type of these expressions is the Nothing type . Break and Continue Labels Any expression in Kotlin may be marked with a label . Labels have the form of an identifier followed by the @ sign, for example: abc@ , fooBar@ are valid labels (see the grammar ). To label an expression, we just put a label in front of it loop@ for (i in 1..100) { // ... } Now, we can qualify a break or a continue with a label: loop@ for (i in 1..100) { for (j in 1..100) { if (...) break@loop } } A break qualified with a label jumps to the execution point right after the loop marked with that label. A contin

Control Flow If Expression In Kotlin, if is an expression, i.e. it returns a value. Therefore there is no ternary operator (condition ? then : else), because ordinary if works fine in this role. // Traditional usage var max = a if (a < b) max = b // With else var max: Int if (a > b) { max = a } else { max = b } // As expression val max = if (a > b) a else b if branches can be blocks, and the last expression is the value of a block: val max = if (a > b) { print("Choose a") a } else { print("Choose b") b } If you're using if as an expression rather than a statement (for example, returning its value or assigning it to a variable), the expression is required to have an else branch. When Expression when replaces the switch operator of C-like languages. In the simplest form it looks like this when (x) { 1 -> print("x == 1") 2 -> print("x == 2") else -> { // Note the

Basic Types In Kotlin, everything is an object in the sense that we can call member functions and properties on any variable. Some types are built-in, because their implementation is optimized, but to the user they look like ordinary classes. In this section we describe most of these types: numbers, characters, booleans and arrays. Numbers Kotlin handles numbers in a way close to Java, but not exactly the same. For example, there are no implicit widening conversions for numbers, and literals are slightly different in some cases. Kotlin provides the following built-in types representing numbers (this is close to Java): Type Bit width Double 64 Float 32 Long 64 Int 32 Short 16 Byte 8 Note that characters are not numbers in Kotlin. Literal Constants There are the following kinds of literal constants for integral values: Decimals: 123 Longs are tagged by a capital L : 123L Hexadecimals: 0x0F Binaries: 0b00001011 NOTE: Octal literals a