ch09

ch09/error_propagation.rs

@@ -0,0 +1,33 @@
+use std::fs::File;
+use std::io::{self, Read};
+
+fn read_username_short() -> Result<String, io::Error> {
+    let mut username_file = File::open("username.txt")?;
+    let mut username = String::new();
+    username_file.read_to_string(&mut username)?;
+    Ok(username)
+}
+
+fn read_username_long() -> Result<String, io::Error> {
+    let file_result = File::open("username.txt");
+
+    let mut username_file = match file_result {
+        Ok(file) => file,
+        Err(e) => return Err(e),
+    };
+
+    let mut username = String::new();
+
+    match username_file.read_to_string(&mut username) {
+        Ok(_) => Ok(username),
+        Err(e) => Err(e),
+    }
+}
+
+fn main() {
+    let username_long = read_username_long().expect("Failed to read username");
+    let username_short = read_username_short().expect("Failed to read username");
+
+    println!("{}", username_long);
+    println!("{}", username_short);
+}