Numbers | Docs [ints, floats, bools]

There are many different numeric types, but usually small subset suffices for most applications:

• u8 or char (alias of the same type) when dealing with strings and raw byte sttreams
• i32 for most standard numeric uses
• usize for counters, indicies and pointer arithmetic
• f32 or f64 depending on precision needs
• u8, u32 or u64 for bit masks or enumerations, depending on variant count
• bool for flags and conditions

You should try staying within a specific numeric type for a usecase, however sometimes you will need to convert between two different types.

For that use std::numcast<T, U>(t: T) -> U to do a C-style cast from a numeric type T to a numeric type U:

let a: u8 = 3;
let b: f32 = 4.2;
let r: f32 = numcast::<u8, f32>(a) * b;

This is equivalent to the following C code:

unsigned char a = 3;
float b = 4.2;
float r = (float)a * b;
// r = 12.6

If you want to instead reinterpret the bytes of a type literally, use std::typecast<T, U>(t: T) -> U, which performs a pointer cast:

let f: f32 = 3.1415;
let f_bytes: u32 = typecast::<f32, u32>(f);
// f_bytes = 0b01000000010010010000111001010110 = 0x40490e56 = 1078529622

This is equivalent to the following C code:

float f = 3.1415;
unsigned int f_bytes = *(unsigned int*)&f;
// f_bytes = 0b01000000010010010000111001010110 = 0x40490e56 = 1078529622

Note: typecast only works for types of same size.