()
| 1 | #[test] |
| 2 | fn vec_random_access() { |
| 3 | // Allocate vector big enough for 4 elements. |
| 4 | let size = 4; |
| 5 | let mut x: Vec<usize> = Vec::with_capacity(size); |
| 6 | let x_ptr = x.as_mut_ptr(); |
| 7 | |
| 8 | unsafe { |
| 9 | for v in 0..4 { |
| 10 | *x_ptr.add(v) = v; |
| 11 | } |
| 12 | x.set_len(size); |
| 13 | } |
| 14 | assert_eq!(&*x, &[0, 1, 2, 3]); |
| 15 | |
| 16 | // 扩充 |
| 17 | x.reserve(4); |
| 18 | let x_ptr = x.as_mut_ptr(); |
| 19 | unsafe { |
| 20 | for v in 4..8 { |
| 21 | *x_ptr.add(v) = v; |
| 22 | } |
| 23 | x.set_len(8) |
| 24 | } |
| 25 | assert_eq!(&*x, &[0, 1, 2, 3, 4, 5, 6, 7]); |
| 26 | } |