Floating-Point Types
Floating-point types include Float16, Float32, and Float64, which are used to represent floating-point numbers (numbers with fractional parts, such as 3.14159, 8.24, and 0.1) with encoding lengths of 16-bit, 32-bit, and 64-bit, respectively. Float16, Float32, and Float64 correspond to the half-precision format (binary16), single-precision format (binary32), and double-precision format (binary64) in IEEE 754.
The precision (number of significant digits) of Float64 is approximately 15 digits, Float32 has a precision of about 6 digits, and Float16 has a precision of about 3 digits. The choice of floating-point type depends on the nature and range of the floating-point numbers to be processed in the code. When multiple floating-point types are suitable, the higher-precision type is preferred because lower-precision types are prone to accumulated calculation errors and have a limited range of precisely representable integers.
Floating-Point Literals
Floating-point literals can be represented in two radix forms: decimal and hexadecimal. In decimal notation, a floating-point literal must contain at least an integer part or a fractional part, and if there is no fractional part, it must include an exponent part (prefixed with e or E, with a base of 10). In hexadecimal notation, a floating-point literal must contain at least an integer part or fractional part (prefixed with 0x or 0X) and must include an exponent part (prefixed with p or P, with a base of 2).
The following examples demonstrate the use of floating-point literals:
When using decimal floating-point literals, the type can be explicitly specified by adding a suffix. The correspondence between suffixes and types is as follows:
| Suffix | Type |
| :----- | :------ |
| f16 | Float16 |
| f32 | Float32 |
| f64 | Float64 |
Floating-point literals with suffixes can be used as shown below:
let a: Float32 = 3.14 // a is 3.140000 with type Float32
let b: Float32 = 2e3 // b is 2000.000000 with type Float32
let c: Float32 = 2.4e-1 // c is 0.240000 with type Float32
let d: Float64 = .123e2 // d is 12.300000 with type Float64
let e: Float64 = 0x1.1p0 // e is 1.062500 with type Float64
let f: Float64 = 0x1p2 // f is 4.000000 with type Float64
let g: Float64 = 0x.2p4 // g is 2.000000 with type Float64let a = 3.14f32 // a is 3.140000 with type Float32
let b = 2e3f32 // b is 2000.000000 with type Float32
let c = 2.4e-1f64 // c is 0.240000 with type Float64
let d = .123e2f64 // d is 12.300000 with type Float64Supported Operations for Floating-Point Types
Floating-point types natively support the following operators: arithmetic operators, relational operators, and compound assignment operators. Floating-point types do not support increment and decrement operators.
Floating-point types can be converted between each other, as well as between floating-point types and integer types. For specific type conversion syntax and rules, refer to Numeric Type Conversions.