Iterate with index in Rust 1.55

To iterate over an array with index in Rust 1.55, you can use the iter() method and the enumerate() method.

Here's an example:

fn main() {
    let a = [10, 20, 30];
for (index, value) in a.iter().enumerate() {

        println!("a[{}] = {}", index, value);

    }

}

In this example, we're iterating over the array a with the iter() method. The enumerate() method returns an iterator that yields tuples containing the index and the value of each item in the array. We're using a for loop to loop over the iterator and print out each tuple.

The output of this program would be:

a[0] = 10
a[1] = 20
a[2] = 30

You can also use pattern matching to unpack the values from the tuple:

fn main() {
    let a = [10, 20, 30];
for (index, &value) in a.iter().enumerate() {

        println!("a[{}] = {}", index, value);

    }

}

In this example, we're using pattern matching to bind the value of each tuple to the variable value. We're using the & operator to create a reference to the value, so we can avoid copying the value. The output of this program would be the same as the previous example.