From 4e9b5735ada47cc391b22a52ae12f6eb39c36fcc Mon Sep 17 00:00:00 2001
From: Kivanc Gunalp <kivancgunalp@gmail.com>
Date: Sun, 26 Jul 2026 15:48:35 +0000
Subject: [PATCH] Use more idiomatic Rust in file_io2/file_io3

- file_io2: replace the manual line_number counter with
  .lines().enumerate(), and replace
  buffered_file_writer.write(format!(...).as_bytes()) with writeln!,
  which both formats and guarantees a complete write (write_fmt loops
  internally, unlike a single Write::write call).
- file_io3: replace the manual match on file_path.parent() with
  .ok_or_else(...)? for a more idiomatic Option-to-Result conversion.

Verified locally: both solutions compile under edition 2024, clippy is
silent, and running them still produces identical output (3 lines
processed / 117-byte file, non-readonly permissions) with no leftover
files.
---
 exercises/24_file_io/file_io2.rs | 17 ++++++++---------
 exercises/24_file_io/file_io3.rs |  7 +++----
 solutions/24_file_io/file_io2.rs | 17 ++++++++---------
 solutions/24_file_io/file_io3.rs |  7 +++----
 4 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/exercises/24_file_io/file_io2.rs b/exercises/24_file_io/file_io2.rs
index 279c17dc..37680891 100644
--- a/exercises/24_file_io/file_io2.rs
+++ b/exercises/24_file_io/file_io2.rs
@@ -24,23 +24,22 @@ fn main() -> Result<(), std::io::Error> {
 
     let mut buffered_file_writer = BufWriter::new(output_file);
 
-    let mut line_number = 1;
+    let mut lines_processed = 0;
 
-    for line in buffered_input_file.lines() {
+    for (index, line) in buffered_input_file.lines().enumerate() {
         let line = line.inspect_err(|err| {
             eprintln!("{} line parse error {:?}", TEST_INPUT_FILE_NAME, err);
         })?;
 
-        buffered_file_writer
-            .write(format!("Line {} : {}\n", line_number, line).as_bytes())
-            .inspect_err(|err| {
-                eprintln!("{} line write error {:?}", TEST_INPUT_FILE_NAME, err);
-            })?;
+        let line_number = index + 1;
+        writeln!(buffered_file_writer, "Line {} : {}", line_number, line).inspect_err(|err| {
+            eprintln!("{} line write error {:?}", TEST_INPUT_FILE_NAME, err);
+        })?;
 
-        line_number += 1;
+        lines_processed = line_number;
     }
 
-    println!("{} : lines processed", line_number - 1);
+    println!("{} : lines processed", lines_processed);
     file_cleanup()
 }
 
diff --git a/exercises/24_file_io/file_io3.rs b/exercises/24_file_io/file_io3.rs
index 0f25c03d..52cc8ed0 100644
--- a/exercises/24_file_io/file_io3.rs
+++ b/exercises/24_file_io/file_io3.rs
@@ -38,10 +38,9 @@ fn main() -> Result<(), std::io::Error> {
 fn create_required_files() -> Result<(), std::io::Error> {
     let file_path = sample_file_path();
 
-    let dir_path = match file_path.parent() {
-        Some(parent) => parent,
-        None => return Err(Error::other("Could not get parent path")),
-    };
+    let dir_path = file_path
+        .parent()
+        .ok_or_else(|| Error::other("Could not get parent path"))?;
 
     if !dir_path.exists() {
         fs::create_dir_all(dir_path).inspect_err(|x| {
diff --git a/solutions/24_file_io/file_io2.rs b/solutions/24_file_io/file_io2.rs
index fd67e70b..4b2cb0f7 100644
--- a/solutions/24_file_io/file_io2.rs
+++ b/solutions/24_file_io/file_io2.rs
@@ -23,23 +23,22 @@ fn main() -> Result<(), std::io::Error> {
 
     let mut buffered_file_writer = BufWriter::new(output_file);
 
-    let mut line_number = 1;
+    let mut lines_processed = 0;
 
-    for line in buffered_input_file.lines() {
+    for (index, line) in buffered_input_file.lines().enumerate() {
         let line = line.inspect_err(|err| {
             eprintln!("{} line parse error {:?}", TEST_INPUT_FILE_NAME, err);
         })?;
 
-        buffered_file_writer
-            .write(format!("Line {} : {}\n", line_number, line).as_bytes())
-            .inspect_err(|err| {
-                eprintln!("{} line write error {:?}", TEST_INPUT_FILE_NAME, err);
-            })?;
+        let line_number = index + 1;
+        writeln!(buffered_file_writer, "Line {} : {}", line_number, line).inspect_err(|err| {
+            eprintln!("{} line write error {:?}", TEST_INPUT_FILE_NAME, err);
+        })?;
 
-        line_number += 1;
+        lines_processed = line_number;
     }
 
-    println!("{} : lines processed", line_number - 1);
+    println!("{} : lines processed", lines_processed);
     file_cleanup()
 }
 
diff --git a/solutions/24_file_io/file_io3.rs b/solutions/24_file_io/file_io3.rs
index c6a05d4e..67557696 100644
--- a/solutions/24_file_io/file_io3.rs
+++ b/solutions/24_file_io/file_io3.rs
@@ -37,10 +37,9 @@ fn main() -> Result<(), std::io::Error> {
 fn create_required_files() -> Result<(), std::io::Error> {
     let file_path = sample_file_path();
 
-    let dir_path = match file_path.parent() {
-        Some(parent) => parent,
-        None => return Err(Error::other("Could not get parent path")),
-    };
+    let dir_path = file_path
+        .parent()
+        .ok_or_else(|| Error::other("Could not get parent path"))?;
 
     if !dir_path.exists() {
         fs::create_dir_all(dir_path).inspect_err(|x| {