67 lines
1.3 KiB
Markdown
67 lines
1.3 KiB
Markdown
1.
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```rust
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struct Array<T, const N: usize> {
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data : [T; N]
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}
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fn main() {
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let arrays = [
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Array{
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data: [1, 2, 3],
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},
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Array {
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data: [1, 2, 3],
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},
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Array {
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data: [1, 2,4]
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}
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];
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}
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```
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2.
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```rust
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fn print_array<T: std::fmt::Debug, const N: usize>(arr: [T; N]) {
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println!("{:?}", arr);
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}
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fn main() {
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let arr = [1, 2, 3];
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print_array(arr);
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let arr = ["hello", "world"];
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print_array(arr);
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}
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```
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3.
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```rust
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#![allow(incomplete_features)]
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#![feature(generic_const_exprs)]
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fn check_size<T>(val: T)
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where
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Assert<{ core::mem::size_of::<T>() < 768 }>: IsTrue,
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{
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//...
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}
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// fix the errors in main
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fn main() {
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check_size([0u8; 767]);
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check_size([0i32; 191]);
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check_size(["hello你好"; 47]); // &str is a string reference, containing a pointer and string length in it, so it takes two word long, in x86-64, 1 word = 8 bytes
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check_size([(); 31].map(|_| "hello你好".to_string())); // String is a smart pointer struct, it has three fields: pointer, length and capacity, each takes 8 bytes
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check_size(['中'; 191]); // A char takes 4 bytes in Rust
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}
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pub enum Assert<const CHECK: bool> {}
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pub trait IsTrue {}
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impl IsTrue for Assert<true> {}
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``` |