From: Martin Pitt <martin@piware.de>
Date: Mon, 23 Aug 2021 12:02:33 +0000 (+0200)
Subject: File reading and error handling using ?
X-Git-Url: https://piware.de/gitweb/?a=commitdiff_plain;h=80e4d9aff6de0cdeaedc8db269a18c6da91d0239;p=learn-rust.git

File reading and error handling using ?
---

diff --git a/src/main.rs b/src/main.rs
index 973bb2e..441cc79 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -69,6 +69,13 @@ fn test_hashmaps() {
     println!("collect_scores after rebuilding with doubling: {:?}", collect_scores);
 }
 
+fn read_file(path: &str) -> Result<String, std::io::Error> {
+    let mut s = String::new();
+    File::open(path)?
+        .read_to_string(&mut s)?;
+    Ok(s)
+}
+
 fn test_files() {
     if let Ok(mut f) = File::open("Cargo.toml") {
         let mut contents = String::new();
@@ -95,6 +102,12 @@ fn test_files() {
         panic!("Could not read file: {:?}", e);
     });
     println!("successfully opened Cargo.toml with unwrap_or_else: {:?}, contents {} bytes:\n{}\n----------", f, len, contents);
+
+    // using the '?' operator
+    match read_file("Cargo.toml") {
+        Ok(s) => println!("Cargo.toml contents:\n{}\n-------------", s),
+        Err(e) => println!("Could not open Cargo.toml: {:?}", e)
+    }
 }
 
 fn main() {