Question

我想将函数的输出写入文件。我希望write_fmt符合我的要求：

use std::{
    fs::File,
    io::{BufWriter, Write},
};

fn main() {
    let write_file = File::create("/tmp/output").unwrap();
    let mut writer = BufWriter::new(&write_file);

    // From my function
    let num = 1;
    let factorial = 1;

    writer.write_fmt("Factorial of {} = {}", num, factorial);
}

错误

error[E0061]: this function takes 1 parameter but 3 parameters were supplied
  --> src/main.rs:11:12
   |
11 |     writer.write_fmt("Factorial of {} = {}", num, factorial);
   |            ^^^^^^^^^ expected 1 parameter

这似乎是错误的，文档中没有多少可用内容。

Answer 1

use std::fs::File;
use std::io::Write;

fn main() {
    let mut w = File::create("/tmp/test.txt").unwrap();
    writeln!(&mut w, "test").unwrap();
    writeln!(&mut w, "formatted {}", "arguments").unwrap();
}

如何将格式化的字符串写入文件？

1 个答案: