Macro alloc::vec 1.0.0[−][src]
macro_rules! vec {
() => { ... };
($elem : expr ; $n : expr) => { ... };
($($x : expr), + $(,) ?) => { ... };
}Expand description
Creates a Vec containing the arguments.
vec! allows Vecs to be defined with the same syntax as array expressions.
There are two forms of this macro:
- Create a
Veccontaining a given list of elements:
let v = vec![1, 2, 3];
assert_eq!(v[0], 1);
assert_eq!(v[1], 2);
assert_eq!(v[2], 3);Run- Create a
Vecfrom a given element and size:
let v = vec![1; 3];
assert_eq!(v, [1, 1, 1]);RunNote that unlike array expressions this syntax supports all elements
which implement Clone and the number of elements doesn’t have to be
a constant.
This will use clone to duplicate an expression, so one should be careful
using this with types having a nonstandard Clone implementation. For
example, vec![Rc::new(1); 5] will create a vector of five references
to the same boxed integer value, not five references pointing to independently
boxed integers.
Also, note that vec![expr; 0] is allowed, and produces an empty vector.
This will still evaluate expr, however, and immediately drop the resulting value, so
be mindful of side effects.