find the length of a linked list in rust

To find the length of a linked list in Rust, we need to traverse the list from the first node to the last node, counting the number of nodes as we go. This can be done using iteration.

Here's an implementation in Rust that uses a mutable reference to the head of the linked list and a counter variable to keep track of the number of nodes:

main.rs
// Define a Node struct representing a node in the linked list
struct Node {
    data: i32,
    next: Option<Box<Node>>,
}

// A function to calculate the length of a linked list
fn list_length(head: &Option<Box<Node>>) -> usize {
    let mut current_node = head;
    let mut count = 0;

    // While there is still a node left to visit
    while let Some(node) = current_node {
        count += 1;
        current_node = &node.next;
    }

    count
}
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In this implementation, we start with a mutable reference to the head of the linked list (head) and initialize the node counter (count) to zero. Then, we enter a loop that continues while current_node is an Option containing a Box<Node>. Since current_node is a mutable reference, we can update it each time we iterate through the loop by setting it to the next node in the list (&node.next). Inside the loop, we increment the count variable by one for each node we visit. Finally, we return the count variable, which contains the length of the linked list.