Print errors to stderr

minigrep/src/main.rs

@@ -7,12 +7,12 @@ fn main() {
     let args: Vec<String> = env::args().collect();
 
     let config = Config::build(&args).unwrap_or_else(|err| {
-        println!("Problem parsing arguments: {err}");
+        eprintln!("Problem parsing arguments: {err}");
         process::exit(1);
     });
 
     if let Err(e) = minigrep::run(config) {
-        println!("Application error: {e}");
+        eprintln!("Application error: {e}");
         process::exit(1);
     }
 }