Rust Notes: From A C++ User

Learn Rust from C++ programmer’s perspective

loop

If we have a vec:

let vec = vec![1, 2, 3];

for range

for i in 0..vec.len() {
    println!("{}, {}", i, match_test(&vec[i]));
}

for each

// type of `item` is &u64
for item in &vec {
    println!("{}", item);
}

If vec is not used as reference here, there will be an implicit move:

//`vec` moved due to this implicit call to `.into_iter()`
for item in vec {
    println!("{}", item);
}

Or we can use iterator, which is not exactly same as we do in C++:

// type of `item` is &u64 
for item in vec.iter() {
    println!("{}", item)
}

Or use enumerate, same as we do in python:

for (index, item) in vec.iter().enumerate() {
    println!("{}, {}", index, item);
}

dead loop

Same as while(true):

let mut i = 0;
loop {
    if i > 2 {
        break;
    }
    println!("{}", vec[i]);
    i += 1;
}

Heap

To allocate memory on heap, use Box<T>:

let x = Box::<usize>::new(20);

Box<T> is very similar to std::unique_ptr<T> in C++. const auto x = std::make_unique<const int>(123) can be written as let x = Box::new(123) in Rust.