Basic Data types
- Numbers
- Boolean
- Characters
- Strings
- Arrays
⇒ Numbers
- Kotlin provides a set of built-in types that represent numbers.
⇒ Integers numbers
- there are four types with different sizes and, hence, value ranges:
Type | Size (bits) | Min value | Max value |
Byte | 8 | -128 | 127 |
Short | 16 | -32768 | 32767 |
Int | 32 | -2,147,483,648
or
( -2^31) | 2,147,483,647
or
( 2^31 -1) |
Long | 64 | -9,223,372,036,854,775,808
or
( -2^63) | 9,223,372,036,854,775,807
or
( 2^63 -1) |
- When you initialize a variable with no explicit type specification, the compiler automatically infers the type with the smallest range enough to represent the value.
- If it is not exceeding the range of Int, the type is Int. If it exceeds, the type is Long.
- To specify the Long value explicitly, append the suffix L to the value. Explicit type specification triggers the compiler to check the value not to exceed the range of the specified type.
val oneLong = 1L // Long
⇒ Floating-Point Numbers
- For real numbers, Kotlin provides floating-point types Float and Double
Type | Size (bits) | Significant bits | Exponent bits | Decimal digits |
Float | 32 | 24 | 8 | 6-7 |
Double | 64 | 53 | 11 | 15-16 |
- You can initialize Double and Float variables with numbers having a fractional part.
- It's separated from the integer part by a period (
.)
val PI = 3.14 //Double
- To explicitly specify the Float type for a value, add the suffix f or F , If such a value contains more than 6-7 decimal digits, it will be rounded:
val e = 2.7182818284 // Double val eFloat = 2.7182818284f // Float, actual value is 2.7182817
Note:Unlike some other languages, there are no implicit widening conversions for numbers in Kotlin. For example, a function with a Double parameter can be called only on Double values, but not Float, Int, or other numeric values:
⇒ Boolean
- The type Boolean represents boolean objects that can have two values: true , false.
- Built-in operations on booleans include:
- || - disjuction ( Logical OR )
- && - Conjuction (Logical AND )
- ! - Negation ( Logical NOT )
fun main() { val myTrue: Boolean = true val myFalse: Boolean = false val boolNull: Boolean? = null println(myTrue || myFalse) println(myTrue && myFalse) println(!myTrue) }
⇒ Characters
- Characters are represented by the type Char.
- Character literals go in single quotes:
' 1 '
- Special characters start from an escaping backslash
\.
- The following escape sequences are supported:
\t\b- backspace\n- new line (LF)\r- carriage return (CR)\’- Single quotation mark\”- Double quotation mark\\- backslash\$- Dollar sign
