diff --git a/src/common_code/common_code.cc b/src/common_code/common_code.cc
index 7a8d646..3a3101e 100644
--- a/src/common_code/common_code.cc
+++ b/src/common_code/common_code.cc
@@ -6,6 +6,10 @@ uint64_t CommonCode::unwrap() const {
     return code; // raw uint64_t code
 }
 
+bool CommonCode::valid() const {
+    return CommonCode::check(code);
+}
+
 CommonCode CommonCode::create(uint64_t common_code) {
     return CommonCode(common_code); // create from uint64_t
 }
@@ -23,6 +27,10 @@ CommonCode::CommonCode(uint64_t common_code) {
     code = common_code;
 }
 
+bool CommonCode::operator==(const CommonCode &common_code) const {
+    return this->code == common_code.code;
+}
+
 std::ostream& operator<<(std::ostream &out, const CommonCode &self) {
     char str[10];
     sprintf(str, "%09lX", self.code);
diff --git a/src/common_code/common_code.h b/src/common_code/common_code.h
index 1f4e502..cbf1d5d 100644
--- a/src/common_code/common_code.h
+++ b/src/common_code/common_code.h
@@ -11,8 +11,12 @@ class ShortCode;
 
 class CommonCode {
 public:
+    bool valid() const;
     static bool check(uint64_t common_code);
+
+    /// Operators of CommonCode
     explicit operator uint64_t() const { return code; }
+    bool operator==(const CommonCode &common_code) const;
     friend std::ostream& operator<<(std::ostream &out, const CommonCode &self);
 
     /// Export functions
diff --git a/src/short_code/short_code.cc b/src/short_code/short_code.cc
index e4c441f..6bdb385 100644
--- a/src/short_code/short_code.cc
+++ b/src/short_code/short_code.cc
@@ -5,6 +5,10 @@ uint32_t ShortCode::unwrap() const {
     return code; // raw uint32_t code
 }
 
+bool ShortCode::valid() const {
+    return ShortCode::check(code);
+}
+
 ShortCode ShortCode::create(uint32_t short_code) {
     return ShortCode(short_code);
 }
@@ -20,6 +24,10 @@ bool ShortCode::check(uint32_t short_code) {
     return short_code < SHORT_CODE_LIMIT; // 0 ~ (SHORT_CODE_LIMIT - 1)
 }
 
+bool ShortCode::operator==(const ShortCode &short_code) const {
+    return this->code == short_code.code;
+}
+
 std::ostream& operator<<(std::ostream &out, const ShortCode &self) {
     out << self.to_string() << "(" << self.code << ")"; // short code info
     return out;
diff --git a/src/short_code/short_code.h b/src/short_code/short_code.h
index 3eea502..01ecde1 100644
--- a/src/short_code/short_code.h
+++ b/src/short_code/short_code.h
@@ -13,9 +13,13 @@ class ShortCode {
 public:
     enum Mode {NORMAL, FAST};
 
+    bool valid() const;
     static void speed_up(enum Mode mode);
     static bool check(uint32_t short_code);
+
+    /// Operators of ShortCode
     explicit operator uint32_t() const { return code; }
+    bool operator==(const ShortCode &short_code) const;
     friend std::ostream& operator<<(std::ostream &out, const ShortCode &self);
 
     /// Export functions