4.5 `Read` 与 `Write`

05-Read 与 Write — Comprehensive Rust

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译文 · 基于 Comprehensive Rust

原文链接: https://google.github.io/comprehensive-rust/std-traits/read-and-write.html

4.5 Read 与 Write

使用 Read 与 BufRead，可以对 u8 源做抽象：

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// Copyright 2023 Google LLC
// SPDX-License-Identifier: Apache-2.0
use std::io::{BufRead, BufReader, Read, Result};

fn count_lines<R: Read>(reader: R) -> usize {
    let buf_reader = BufReader::new(reader);
    buf_reader.lines().count()
}

fn main() -> Result<()> {
    let slice: &[u8] = b"foo\nbar\nbaz\n";
    println!("lines in slice: {}", count_lines(slice));

    let file = std::fs::File::open(std::env::current_exe()?)?;
    println!("lines in file: {}", count_lines(file));
    Ok(())
}

类似地，Write 让你对 u8 汇点做抽象：

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// Copyright 2023 Google LLC
// SPDX-License-Identifier: Apache-2.0
use std::io::{Result, Write};

fn log<W: Write>(writer: &mut W, msg: &str) -> Result<()> {
    writer.write_all(msg.as_bytes())?;
    writer.write_all("\n".as_bytes())
}

fn main() -> Result<()> {
    let mut buffer = Vec::new();
    log(&mut buffer, "Hello")?;
    log(&mut buffer, "World")?;
    println!("Logged: {buffer:?}");
    Ok(())
}
最后修改 August 11, 2026: 更新 (70a5af133)