File Read

Read files with std::fs.

Difficulty

Intermediate

Code

use std::fs;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // read entire file
    let content = fs::read_to_string("Cargo.toml")?;
    println!("first line: {}", content.lines().next().unwrap_or(""));

    // read bytes
    let bytes = fs::read("Cargo.toml")?;
    println!("file size: {} bytes", bytes.len());

    Ok(())
}

Explanation

fs::read_to_string reads files into strings.

Key Concepts

• Read the code carefully and understand the data flow
• Try modifying the example to see how it changes behavior
• Run this code in the Rust Playground

Related Topics

Browse more examples in the file-io category to build a complete understanding of this topic.