Vectors in Rust Programming

Vectors in Rust are like re-sizable arrays. They are used to store objects that are of the same type and they are stored contiguously in memory

Like Slices, their size is not known at compile-time and can grow or shrink accordingly. It is denoted by Vec<T> in Rust

The data stored in the vector is allocated on the heap.

Example

In the below example, a vector named d is created using the Vec::new(); function that Rust provides.

fn main() {    let mut d: Vec = Vec::new();    d.push(10);    d.push(11);    println!("{:?}", d);    d.pop();    println!("{:?}", d); }

We push the elements into a vector using the push() function and we remove the elements using the pop() function.

Output

[10, 11] [10]

Rust also provides us with another way to create a vector. Instead of using the Vec::new() function, we can make use of vec! Macro.

Example

Live Demo

fn main() {    let v = vec![1,2,3];    println!("{:?}",v); }

Output

[1, 2, 3]

The above vector is not mutable and if we try to mutate some of its values, then we will get an error.

Example

Live Demo

fn main() {    let v = vec![1,2,3];    println!("{:?}",v);    v[0] = 99;    println!("{:?}",v); }

Output

  | 4 | let v = vec![1,2,3];   | - help: consider changing this to be mutable: `mut v` 5 | println!("{:?}",v); 6 | v[0] = 99; | ^ cannot borrow as mutable

We can make it mutable by adding the mut keyword in front of the name of the vector we are defining.

Example

Live Demo

fn main() {    let mut v = vec![1,2,3];    println!("{:?}",v);    v[0] = 99;    println!("{:?}",v); }

Output

[1, 2, 3] [99, 2, 3]

Lastly, it should be remembered that whenever the length of the vector exceeds the capacity, then the capacity of the vector will be increased automatically.