Why does my line from BufReader::lines not match?

Question

I am trying to parse a text file and find if a string is equal to current line I am on using BufReader:

let mut chapter = String::from("Chapter 1\n");

//open file
let file = File::open("document.txt")?;
let reader = BufReader::new(file);

for line in reader.lines() {
    if chapter.eq(&line.unwrap()) {
        println!("chapter found!");
    }
}

However, the if statement never returns true. How can I properly convert line from reader.lines() into a way I can find a match?

Shepmaster · Accepted Answer · 2020-11-15T14:48:54.663

From the documentation of ReadBuf::lines:

Each string returned will not have a newline byte (the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.

Remove the \n from your search string:

let mut chapter = String::from("Chapter 1");

There's no reason to allocate the String here. A number of other changes:

use std::{
    fs::File,
    io::{self, BufRead, BufReader},
};

fn example() -> io::Result<()> {
    let chapter = "Chapter 1";

    let file = File::open("document.txt")?;
    let reader = BufReader::new(file);

    for line in reader.lines() {
        if chapter == line.unwrap() {
            println!("chapter found!");
        }
    }

    Ok(())
}

Why does my line from BufReader::lines not match?

1 Answers1