HashMaps
use std::collections::HashMap; |
let mut h: HashMap<(i64,i64),i64> = HashMap::new(); |
h.contains_key(&(n,k)) |
check whether key is present |
h.insert((n,k), res); |
insert new value |
*h.get(&(n,k)).unwrap() |
retrieve value |
Variables and constants
const N: i32 = 5 |
(Global) constant |
let v = vec![3, 1, 4] |
Define and initialize vector |
let zero_vec = vec![0; len] |
let mut p : [usize; 9] = [0; 9]; |
Primitive types
bool |
Boolean |
char |
character |
f32, f64 |
32-bits, 64-bits floats |
i64, i32, i16, i8 |
signed 16- ... integers |
u64, u32, u16, u8 |
unsigned 16-bits, ... integers |
isize |
pointer-sized signed integers |
usize |
pointer-sized unsigned integers |
Processor directives
|
#![feature(iterator_step_by)] for n in (0..100).step_by(2) { ... } iterates over even numbers
|
|
#![feature(inclusive_range_syntax)] 1..=n is a range which includes both 1 and n
|
|
|
Boolean operators
Operator |
Syntax |
And |
a & b or a && b |
Or |
a . b or a .. b |
And |
a ^ b |
Not |
!a |
Conversions
To convert say an n: i32
to a u64
use n as u64
|
To convert a number x
to a string use x.to_string()
|
To convert s: String*
to x.parse().unwrap()
|
x.unwrap_or(default_value)
|
Formatting
println!("{}", x); |
println!("{:010b}", x); |
binary, 10 digits, print leading zeros |
format!("Hello"); |
"Hello" |
format!("Hello, {}!", "world"); |
"Hello, world!" |
format!("The number is {}", 1); |
"The number is 1" |
format!("{:?}", (3, 4)); |
"4" |
format!("{value}", value=4); |
"1 2" |
format!("{:04}", 42); |
"0042" with leading zeros |
Vectors and iterators
(0..16usize).map(|x| x.count_ones() as usize).collect() |
Assertions
let x = 42;
assert!(x == 42);
assert_eq!(x, 42);
|
Use the macro assert!
to check for a boolean true, and assert_eq!
for the equality of two expressions.
|
