How can i list out the contents of an array line by line using the rust programing language
for example the array [1, 2] when inputed would return
1
2
the code needs to be fast.
The following rust code can be used to print an array line by line. 
I've wrapped it in a main function for easy execution:

```
fn main() {
	let arr:[i32; 2] = [1,2];

	for index in 0..arr.len() {
		println!({}, arr[index]);
	}
}
```

Output:
```
1
2
```

Please note that the Rust println function can also print the contents of an array directly:
```
fn main() {
	let arr:[i32; 2] = [1,2];
	println!(Array {:?}, arr);
}
```

Output:
```
    Array [1, 2]
```

This doesn't match the requirement of printing the output line-by-line as stated in the question. I wanted to mention it, as it's short and easy to remember, and might suffice for debugging purpose. However, if you need the response line-by-line, use the first example.
Would you recommend this approach for arrays of sizes in the millions? What other approaches could I take and what would their advantages and disadvantages be with respect to the options given above?
For arrays with millions of elements, printing each element one by one like in the code you posted could be very slow and could also consume a large amount of memory. In such cases, you may want to consider a different approach.

One option would be to process the data in chunks and only print a portion of the data at a time. For example, you could process and print 1000 elements at a time, and then pause and wait for user input before continuing. This way, you can control the amount of memory used and avoid overwhelming the system with too much data.

Another option would be to store the data in a file instead of printing it to the screen. This way, you can access the data at a later time without having to re-process it, and you can also process the data in a more efficient way by reading and writing to the file in large blocks, rather than one element at a time.

Both of these approaches have their advantages and disadvantages, and the best approach depends on the specific use case. Chunking the data and printing in portions may be easier to implement and requires less memory, but it may be less convenient for the user as they will need to manually manage the data processing. Storing the data in a file requires more memory, but it allows for more efficient processing and can be more convenient for the user as they can access the data at a later time.

Ultimately, the choice of approach will depend on the specific requirements of your project and the trade-offs you are willing to make in terms of memory usage, processing time, and user experience.