A vector, written Vec, is Rust’s growable collection for values that all share one type. Unlike an array, its size can change while the program runs. section 3.1.2 section 3.3
Create and use vectors in several straightforward ways:
- Use Vec::new() with push(); Rust can infer the element type from the values you add. section 3.1.2
- Write the type explicitly, such as Vec<String>, when the compiler needs guidance. section 3.1.2
- Use the vec! macro for compact initialization, such as vec![8, 10, 10]. section 3.1.2
- Keep every element the same type; Vec<String> cannot accept an i32. section 3.1.2
- Take slices with ranges, including a middle range, an open-ended range, or the complete vector. section 3.1.2
Vectors allocate memory on the heap and track capacity, the amount of space currently reserved. Pushing values uses that space; when it is exceeded, the capacity can grow, shown by examples changing from 4 to 8. Vec::with_capacity lets you reserve space in advance. section 3.1.2
A growable list of names
let mut names = Vec::new(); names.push(String::from("Windy")); names.push(String::from("Gomesy")); The vector starts empty, then grows as two String values are pushed into it.
fn main() {
let mut my_vec = vec![8, 10, 10];
}
Inspect the compact vec! macro example to see how several values can initialize a vector at once. section 3.1.2
