To create a new empty vector in Rust, we can use the Vec::new() function. This will create a vector with a capacity of 0, meaning that it can initially hold no elements. We can then add elements to the vector using the push() method.
// Create an empty vector.
let v: Vec<i32> = Vec::new();
// Add some elements to the vector.
v.push(1);
v.push(2);
v.push(3);
We can also use the vec! macro to create a vector with initial values. This is a more convenient way to create a vector, especially if we want to initialize it with a lot of values.
// Create a vector with initial values.
let v = vec![1, 2, 3];
Rust will infer the type of the vector from the types of the values that we initialize it with. In the example above, the type of the vector is Vec<i32> because we initialized it with integer values.
Vectors are dynamic arrays, which means that they can grow and shrink as needed. When we add an element to a vector, Rust will automatically allocate more memory for the vector if needed.
We can also specify a capacity for a vector when we create it. This is the number of elements that the vector can hold without reallocating. If we add more elements to the vector than its capacity, Rust will reallocate the vector to a larger size.
// Create a vector with a capacity of 10.
let v: Vec<i32> = Vec::with_capacity(10);
Specifying a capacity can be useful if we know how many elements the vector will need to hold. This can help to avoid unnecessary reallocations, which can improve the performance of our program.
Creating a new vector in Rust is a simple process. We can use the Vec::new() function or the vec! macro to create a new vector. If we need to specify a capacity for the vector, we can use the Vec::with_capacity() function.
