Yes there are. Search for “bigint” on crates.io and there are plenty of results. They are not in the standard library but that’s nothing unusual for Rust. Rust’s standard library is kept small intentionally to minimise binary size ease maintenance (among other reasons). Because Rust is not Python, and there’s no reason for it to … Read more
Texts have many different meaning and usages, so the question is difficult to answer. First: about codepoint. We uses the term codepoint because it is easy, it implies a number (code), and not really confuseable with other terms. Unicode tell us that it doesn’t use the term codepoint and character in a consistent way, but … Read more
No, directly, you can’t. When a function is called from an HTML page, it’s runned by the client’s browser. A modern browser can only run javascript and webassembly. In case you don’t know, webassembly is a low level, assembly like language that your browser can run. Rust projects can be compiled into webassembly and used … Read more
I think this may help you. #[derive(Debug)] enum Fruit { Apple(String), Banana(String), } #[derive(Debug)] struct Test { A: Box<Fruit>, } fn main() { let test = Test { A: Box::new(Fruit::Apple(“apple”.to_string())), }; println!(“{:?}”, test) } 1 solved Create the type of Box
In C++, you split files by reading the master and writing to one or more new files. This technique works with the C language also. Joining files depends if you want to merge or append. In the append case, the destination file is opened with the “append” and write attribute. The file pointer is set … Read more
That block defines a new trait called Foo, which then allows you to use the trait in various places such as the impl block you have posted. The : Bar part says that any type that implements Foo must also implement the Bar trait. 0 solved Traits and Rust
In your comments, you state: I don’t want to use [mod functions] because it will search for settings/functions.rs, and it is not i want to Have you tried that? Assuming you’ve declared the module correctly … this is exactly what you want. main.rs: mod functions; mod settings; fn main() { … } settings.rs: use functions; … Read more
Could the Rust program be written in an idiomatic way, to execute faster? Yes. To create a vector with a few elements, use the vec![] macro: let mut work: Vec<f64> = vec![0.0, 1.0]; for _x in 1..100000000 { work.swap(0, 1); } So is this code faster? Yes. Have a look at what assembly is generated: … Read more
Is there a better way to fix this Yes, but not in stable Rust. You need non-lexical lifetimes: #![feature(nll)] #[derive(Debug)] struct Foo(u32); fn get_foo(bar: &mut Foo) -> Option<&mut u32> { Some(&mut bar.0) } pub fn test() { let x = 5; let y = 6; let mut a = Foo(x); let b = get_foo(&mut a); … Read more
To achieve that, we need a way to store the instances into a list of some kind, and return the index of the list to C++, so it works like a pointer to a Rust struct. I can’t see why this would be the case. You don’t need a static list to return pointers from … Read more
I happen to have this program on hand since it’s a common problem on “coding challenge” websites. You have to decompose the number into groups of 3 digits each and then call the function for serializing the number into text recursively. Here’s the full solution: use std::iter::successors; const ONES: [&str; 20] = [ “zero”, “one”, … Read more
It looks like you want a generic function, so define one directly: #![feature(type_alias_impl_trait)] fn main() { type Mapper<A, B> = impl Fn(Vec<A>) -> Vec<B>; //type Map<A, B> = fn(fn(A) -> B) -> Mapper<A, B>; //let map: Map::<A, B> = |f| move |a: Vec<A>| a.into_iter().map(f).collect(); fn map2<A, B>(f: fn(A) -> B) -> Mapper<A, B> { move … Read more
What have you tried? The straight translation of your example works: fn main() { let mut a = vec![]; a.push(vec![1, 2]); a.push(vec![1, 2, 3]); a.push(vec![1, 2, 3, 4]); a.push(vec![1, 2, 3]); println!(“{:?}”, a); } Playground solved How to add variable length array into a Vec?
The problem is that you are pushing to the Vec a borrowed value: &record[i]. The & means borrow, and as a consequence the original value record must outlive the borrower vec. That might seem fine (both are in the for body, and thus both have the same lifetime, i.e., they both live inside the for … Read more
foo: &Foo is a reference to a Foo, while foo: Foo is a Foo value. The first signature declares that the function only borrows foo by taking a reference, the second signature declares that it takes ownership of the value. Although both compile, and both are correct, there is a difference in how you call … Read more