diff --git a/db/db_impl.cc b/db/db_impl.cc
index 62824ed..35490a6 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -11,6 +11,9 @@
 #include <set>
 #include <string>
 #include <vector>
+#include <cstring>  // For memcpy
+#include <ctime>    // For std::time
+
 
 #include "db/builder.h"
 #include "db/db_iter.h"
@@ -34,11 +37,41 @@
 #include "util/coding.h"
 #include "util/logging.h"
 #include "util/mutexlock.h"
+#include "db_impl.h"
 
 namespace leveldb {
 
 const int kNumNonTableCacheFiles = 10;
 
+//TTL ToDo : add func for TTL Put
+
+void AppendExpirationTime(std::string* value, uint64_t expiration_time) {
+  // 将过期时间戳（64位整数）附加到值的前面
+  value->append(reinterpret_cast<const char*>(&expiration_time), sizeof(expiration_time));
+}
+
+uint64_t GetCurrentTime() {
+  // 返回当前的Unix时间戳
+  return static_cast<uint64_t>(time(nullptr));
+}
+
+// 解析过期时间戳
+uint64_t ParseExpirationTime(const std::string& value) {
+  // 假设过期时间戳在值的前 8 字节，以大端序存储
+  assert(value.size() >= sizeof(uint64_t));
+  uint64_t expiration_time;
+  memcpy(&expiration_time, value.data(), sizeof(uint64_t));
+  return expiration_time;
+}
+
+// 解析出实际的值（去掉前面的过期时间戳部分）
+std::string ParseActualValue(const std::string& value) {
+  // 去掉前 8 字节（存储过期时间戳），返回实际值
+  return value.substr(sizeof(uint64_t));
+}
+
+//finish modify
+
 // Information kept for every waiting writer
 struct DBImpl::Writer {
   explicit Writer(port::Mutex* mu)
@@ -1650,33 +1683,5 @@ Status DestroyDB(const std::string& dbname, const Options& options) {
   return result;
 }
 
-// TTL ToDo: add func for TTL get
-uint64_t ParseExpirationTime(const std::string& value) {
-  // 假设时间戳存储在值的前8个字节（64位整数）
-  uint64_t expiration_time;
-  memcpy(&expiration_time, value.data(), sizeof(uint64_t));
-  return expiration_time;
-}
-
-std::string ParseActualValue(const std::string& value) {
-  // 假设实际值存储在过期时间戳之后
-  return value.substr(sizeof(uint64_t));
-}
-
-//finish modify
-
-//TTL ToDo : add func for TTL Put
-
-void AppendExpirationTime(std::string* value, uint64_t expiration_time) {
-  // 将过期时间戳（64位整数）附加到值的前面
-  value->append(reinterpret_cast<const char*>(&expiration_time), sizeof(expiration_time));
-}
-
-uint64_t GetCurrentTime() {
-  // 返回当前的Unix时间戳
-  return static_cast<uint64_t>(time(nullptr));
-}
-
-//finish modify
 
-}  // namespace leveldb
+}  // namespace leveldb
\ No newline at end of file
diff --git a/db/db_impl.h b/db/db_impl.h
index c7b0172..9c3085f 100644
--- a/db/db_impl.h
+++ b/db/db_impl.h
@@ -38,6 +38,9 @@ class DBImpl : public DB {
   // Implementations of the DB interface
   Status Put(const WriteOptions&, const Slice& key,
              const Slice& value) override;
+  //TTL ToDo
+  Status Put(const WriteOptions& o, const Slice& key, const Slice& val,
+             uint64_t ttl);
   Status Delete(const WriteOptions&, const Slice& key) override;
   Status Write(const WriteOptions& options, WriteBatch* updates) override;
   Status Get(const ReadOptions& options, const Slice& key,