This recipe is going to be a bit longer than the others, because:
- The vector is the most important collection
- Many of its core principles, like preallocation, apply to other collections as well
- It includes methods used on slices, which are also usable by many other collections
Let's start at the beginning.
A vector can be created [9] by using the constructor pattern we mentioned earlier (Chapter 1, Learning the Basics, Using the Constructor Pattern), and filled by calling push on it for every element we want to store [10]. Because this is such a common pattern, Rust provides you with a convenient macro called vec![3]. While its end effect is the same, the macro is implemented with some nice performance optimizations.
Because of the convenience vec! provides, other Rustacians have implemented similar macros for the other collections, which you can find here: https://crates.io/crates/maplit.
If you want to initialize a vector by repeating an element over and over...