How to use the same iterator twice, once for counting and once for iteration?

Question

It seems that an iterator is consumed when counting. How can I use the same iterator for counting and then iterate on it?

I\'m trying to count the lines in a file an

Answer 1

The other answers have already well-explained that you can either recreate your iterator or clone it.

If the act of iteration is overly expensive or it's impossible to do multiple times (such as reading from a network socket), an alternative solution is to create a collection of the iterator's values that will allow you to get the length and the values.

This does require storing every value from the iterator; there's no such thing as a free lunch!

use std::fs;

fn main() {
    let log_content = fs::read_to_string("/home/myuser/test.log").unwrap();
    let lines: Vec<_> = log_content.lines().collect();

    println!("{} lines", lines.len());
    for value in lines {
        println!("{}", value);
    }
}