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Rust program to replace a word in a file

Rust | File I/O Example: Write a program to replace a word in a file.
Submitted by Nidhi, on October 31, 2021

Problem Solution:

In this program, we will open a text file and replace the word in the text file and print the appropriate message.

Program/Source Code:

The source code to replace a word in a file is given below. The given program is compiled and executed on UBUNTU 18.04 successfully.

// Rust program to replace a word in a file

use std::fs::File;
use std::io::{self, Read, Write};

fn main() {
    // Handle errors
    run().unwrap();
}

fn run() -> Result<(), io::Error> {

    let word_from = "Friends";
    let word_to = "World";
    
    let mut source= File::open("sample.txt")?;
    let mut data1 = String::new();
    
    source.read_to_string(&mut data1)?;
    
    drop(source); 

    let data2 = data1.replace(&*word_from, &*word_to);


    let mut dest = File::create("sample.txt")?;
    dest.write(data2.as_bytes())?;

    println!("World replaced in sample.txt successfully");

    Ok(())
}

Output:

$ cat sample.txt 
Hello Friends
Hello India

$ rustc main.rs

$ ./main
World replaced in sample.txt successfully

$ cat sample.txt 
Hello World
Hello India

Explanation:

In the above program, we created a function run() and main(). The run() is a special type of function, it can handle generated errors. And, we replaced the specific word with another word in a file. In the main() function, we called the run() method and replace a specific word in the file with another word, and printed the appropriate message.

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