[英]Rust - Get value from method without borrowing (count the lines of file)
I'm quite new in rust and I have no idea how to workaround.我是 rust 的新手,我不知道如何解决。 The code is:
代码是:
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...
}
The error I've got:我遇到的错误:
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
Please help, I'm stuck on this.请帮忙,我坚持这个。
Calling BufReader::new(file_handle);
调用
BufReader::new(file_handle);
consumes the file_handle
and calling buffered.lines()
consumes buffered
.消耗
file_handle
并调用buffered.lines()
消耗buffered
。 There might be a more efficient, clever, or elegant way to do this but you can open and iterate over the file twice if you want to first get the full line count:可能有一种更有效、更聪明或更优雅的方式来执行此操作,但如果您想首先获得完整的行数,您可以打开并遍历文件两次:
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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