Questions tagged [vec]
78 questions
2
votes
1 answer
What to use instead of `std::lower_bound` and `std::upper_bound` in Rust?
What we have in C++
C++ has two STL functions: std::lower_bound and std::upper_bound
std::lower_bound finds first position of searched value if it exists, or position of first value greater.
std::upper_bound finds first position with greater value…
Angelicos Phosphoros
- 2,469
- 9
- 24
2
votes
1 answer
Why elements should be dropped before dropping vec in rust
I am trying to implement a vector. I found this code where the writer deallocates a vector:
impl Drop for MyVec {
fn drop(&mut self) {
if self.cap != 0 {
while let Some(_) = self.pop() { }
let layout =…
user19291301
- 127
- 8
2
votes
1 answer
How can I make Rust, with the Rodio crate, load multiple sources in a Vec, so I can play them later as needed without having to load them every time?
I am using Rust with the Rodio crate and I wanted to make a Vec of loaded sources to use whenever they are needed, so that the program doesn't need to load it every time. I've made a SoundHandler class that contains an OutputStream, an…
Felipe
- 23
- 5
2
votes
1 answer
How to return a Result?
I want a function to take in a reference to input and return a value if the input is valid or an error if its invalid. Here's my attempt but I get an error:
use std::num::ParseIntError;
fn get_fourth(input: &Vec) -> Result…
curlywei
- 682
- 10
- 18
2
votes
2 answers
How to modify the &mut self contents and return self
I am having a struct and respective impl (add_account) as well.
Struct
pub struct Departments {
pub id: String,
pub linked_accounts: Vec,
}
Impl
impl Departments {
pub fn add_account(&mut self, acct: Account) -> Self {
…
Arul
- 23
- 4
2
votes
2 answers
How to check if a value in a Vec is None?
I would like to use the fact that Vec.last() returns a None if there is nothing at that index but that index still exists. The problem is that I can't find a way to compare the result to anything inside of a while or if. I can however compare it if…
Merlin1846
- 43
- 6
2
votes
1 answer
Read::read_exact does not fill buffer
I have the following code:
use std::io::{Cursor, BufReader, Read};
fn main() {
let string = String::from("Cello");
let bytes = string.as_bytes();
let cursor = Cursor::new(bytes);
let mut reader = BufReader::new(cursor);
let mut…
abipip
- 21
- 2
2
votes
1 answer
How can I modify a part of bigger slice (or Vec) by passing another smaller slice?
How can I correctly implement this code below?
let mut bigger: [u8; 100] = [0u8; 100];
let smaller: [u8; 3] = [1, 2, 3];
// do something like:
// bigger[0..3] = smaller;
Visual Eugen
- 33
- 5
2
votes
1 answer
How to turn two nested HashMaps in a Vec of tuples without for loops?
Take the following data type:
let mut items = HashMap::>::new();
I successfully managed to turn it into a vector of tuples like this:
let mut vector_of_tuples: Vec<(u64, u64, bool)> = vec![];
for (outer_id, inner_hash_map)…
Paul Razvan Berg
- 16,949
- 9
- 76
- 114
2
votes
1 answer
Reading a large file line by line and avoiding utf8 errors in Rust
I have a really large file that "should" consist of JSON strings. However, when I use the following code, I get a "stream did not contain valid UTF8".
let file = File::open("foo.txt")?;
let reader = BufReader::new(file);
for line in reader.lines()…
Ads Sengupta
- 23
- 2
1
vote
1 answer
How did it get converted into 1 line of code from 3 lines? Remapping uv and fixing aspect ratio in shaders
How would you get from this
vec2 uv = fragCoord/iResolution.xy; // <0, 1>
uv -= 0.5; // <-0.5,0.5>
uv.x *= iResolution.x/iResolution.y; // fix aspect ratio
to this?
vec2 uv = (fragCoord - .5 * iResolution.xy) / iResolution.y; // Condense 3 lines…
Artyom Chernyaev
- 13
- 3
1
vote
1 answer
Sort a vector of structs by an f64 value
I am trying to sort a vector of Substance structs:
#[derive(Debug, PartialOrd, PartialEq)]
struct Substance {
price: i32,
mass_kg: i32,
price_per_kg: f64,
}
by price_per_kg my current sorting code is:
// `substances` is a `vec` of…
Pioneer_11
- 670
- 4
- 19
1
vote
2 answers
rust elementwise diff of vec?
What's the most idiomatic way to get the Rust vec equivalent of this Python code?
import numpy as np
a = np.arange(5)
a_diff = np.diff(a) # this is the thing I'm trying to emulate in Rust
print(a_diff) # [1 1 1 1]
I can figure out multiple…
Chad
- 1,434
- 1
- 15
- 30
1
vote
1 answer
Ranges (double-dot ".." operator) with multiplication operator
I recently came across this expression in some code written by GUILLAUME ENDIGNOUX, which produces a vector of 10 numbers:
(10 * i..10 * (i + 1)).collect()
Gives: 420, 421, 422, 423, 424, 425, 426, 427, 428, 429
Here is a working example, where I…
Steinar Cook
- 13
- 4
1
vote
2 answers
How to destructure n items from a vec into variables?
In JavaScript, I can destructure an array in the following way:
const [first, second, ...rest] = myArray
Is there a similar way to achieve this in rust?
If I only want one element, it's easy. I can do:
let first = my_vec[0];
or if I make an array…
Emanuel Lindström
- 1,607
- 16
- 25