diff --git a/src/main.rs b/src/main.rs
index 0b103a1..a7083fe 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,24 +55,21 @@ fn main() -> XResult<()> {
         return Ok(());
     }
 
-    let the_algo = options.algorithm.to_uppercase();
+    let the_algo: &str = &options.algorithm.to_uppercase();
     if options.file_name_list.is_empty() {
-        let boxed_digest = get_digest_by_algorithm(the_algo.as_str(), &options);
-        match boxed_digest {
+        match get_digest_by_algorithm(the_algo, &options) {
             Some(mut digest) => println!("{}  - ({})", calc_digest_stdin(&mut *digest)?, the_algo),
-            None => match the_algo.as_str() {
+            None => match the_algo {
                 "SM3" => println!("{} - ({})", hex::encode(Sm3Hash::new(&read_full_stdin()?).get_hash()), the_algo),
                 _ => print_message(MessageType::ERROR, &format!("Unknown algorithm: {}", options.algorithm)),
             },
         };
     } else {
-        for f in &options.file_name_list {
-            let the_fn = f.as_str();
-            let boxed_digest = get_digest_by_algorithm(the_algo.as_str(), &options);
-            match boxed_digest {
-                Some(mut digest) => println!("{}  - {} ({})", calc_file_digest(&mut *digest, the_fn)?, the_fn, the_algo),
-                None => match the_algo.as_str() {
-                    "SM3" => println!("{}  - {} ({})", hex::encode(Sm3Hash::new(&read_file_full(the_fn)?).get_hash()), the_fn, the_algo),
+        for file in &options.file_name_list {
+            match get_digest_by_algorithm(the_algo, &options) {
+                Some(mut digest) => println!("{}  - {} ({})", calc_file_digest(&mut *digest, file)?, file, the_algo),
+                None => match the_algo {
+                    "SM3" => println!("{}  - {} ({})", hex::encode(Sm3Hash::new(&read_file_full(file)?).get_hash()), file, the_algo),
                     _ => {
                         print_message(MessageType::ERROR, &format!("Unknown algorithm: {}", options.algorithm));
                         return Ok(());