[英]Rust - Get value from method without borrowing (count the lines of file)
我是 rust 的新手,我不知道如何解決。 代碼是:
let input = File::open(file_path)?;
let buffered = BufReader::new(input);
let line_count = buffered.lines().count();
for (nr, line) in buffered.lines().enumerate() {
print!("\rLOADED: [{}/{}]", nr, line_count);
// do something...
}
我遇到的錯誤:
let buffered = BufReader::new(input);
-------- move occurs because `buffered` has type `std::io::BufReader<std::fs::File>`, which does not implement the `Copy` trait
let line_count = buffered.lines().count();
-------- value moved here
for (nr, line) in buffered.lines().enumerate() {
^^^^^^^^ value used here after move
請幫忙,我堅持這個。
調用BufReader::new(file_handle);
消耗file_handle
並調用buffered.lines()
消耗buffered
。 可能有一種更有效、更聰明或更優雅的方式來執行此操作,但如果您想首先獲得完整的行數,您可以打開並遍歷文件兩次:
use std::fs::File;
use std::io::{self, BufRead, BufReader};
fn main() -> io::Result<()> {
let file_path = "input.txt";
let input = File::open(file_path)?;
let buffered = BufReader::new(input);
let line_count = buffered.lines().count();
let input = File::open(file_path)?;
let buffered = BufReader::new(input);
for (nr, line) in buffered.lines().enumerate() {
println!("LOADED: [{}/{}]", nr, line_count);
}
Ok(())
}
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