解决末行无法打印问题 (#783)

* 解决末行无法打印问题

* Apply suggestions from code review

Co-authored-by: ᴜɴᴋɴᴡᴏɴ <u@gogs.io>

eBook/12.5.md

@@ -20,10 +20,10 @@ import (
 func cat(r *bufio.Reader) {
 	for {
 		buf, err := r.ReadBytes('\n')
+		fmt.Fprintf(os.Stdout, "%s", buf)
 		if err == io.EOF {
 			break
 		}
-		fmt.Fprintf(os.Stdout, "%s", buf)
 	}
 	return
 }