diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ec954ad..2a943e9 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -44,14 +44,14 @@ FILES
     yycc/string.hpp
     yycc/string/reinterpret.hpp
     yycc/string/op.hpp
-    yycc/string/parse.hpp
-    yycc/string/stringify.hpp
+    yycc/num/parse.hpp
+    yycc/num/stringify.hpp
     yycc/rust/primitive.hpp
     yycc/rust/panic.hpp
     yycc/rust/option.hpp
     yycc/rust/result.hpp
-    yycc/rust/parse.hpp
-    yycc/rust/stringify.hpp
+    yycc/rust/num/parse.hpp
+    yycc/rust/num/stringify.hpp
     yycc/windows/unsafe_suppressor.hpp
     yycc/windows/import_guard_head.hpp
     yycc/windows/import_guard_tail.hpp
diff --git a/src/yycc/encoding/iconv.cpp b/src/yycc/encoding/iconv.cpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/iconv.hpp b/src/yycc/encoding/iconv.hpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/united_codec.cpp b/src/yycc/encoding/united_codec.cpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/united_codec.hpp b/src/yycc/encoding/united_codec.hpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/utf.hpp b/src/yycc/encoding/utf.hpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/windows.cpp b/src/yycc/encoding/windows.cpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/encoding/windows.hpp b/src/yycc/encoding/windows.hpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/yycc/string/parse.hpp b/src/yycc/num/parse.hpp
similarity index 99%
rename from src/yycc/string/parse.hpp
rename to src/yycc/num/parse.hpp
index a55b4ec..5c0fb91 100644
--- a/src/yycc/string/parse.hpp
+++ b/src/yycc/num/parse.hpp
@@ -1,7 +1,7 @@
 #pragma once
 #include "../string.hpp"
-#include "op.hpp"
-#include "reinterpret.hpp"
+#include "../string/op.hpp"
+#include "../string/reinterpret.hpp"
 #include <charconv>
 #include <stdexcept>
 #include <type_traits>
@@ -18,7 +18,7 @@
  * and boolean values. It uses \c std::from_chars internally for efficient parsing.
  * @remarks See https://zh.cppreference.com/w/cpp/utility/from_chars for underlying called functions.
  */
-namespace yycc::string::parse {
+namespace yycc::num::parse {
 
     /// @private
     /// @brief The error kind when parsing string into number.
diff --git a/src/yycc/string/stringify.hpp b/src/yycc/num/stringify.hpp
similarity index 98%
rename from src/yycc/string/stringify.hpp
rename to src/yycc/num/stringify.hpp
index aebcff8..1a048be 100644
--- a/src/yycc/string/stringify.hpp
+++ b/src/yycc/num/stringify.hpp
@@ -1,6 +1,6 @@
 #pragma once
 #include "../string.hpp"
-#include "reinterpret.hpp"
+#include "../string/reinterpret.hpp"
 #include <array>
 #include <charconv>
 #include <stdexcept>
@@ -18,7 +18,7 @@
  * See https://en.cppreference.com/w/cpp/utility/to_chars for underlying called functions.
  * Default float precision = 6 is gotten from: https://en.cppreference.com/w/c/io/fprintf
  */
-namespace yycc::string::stringify {
+namespace yycc::num::stringify {
 
     /// @private
     /// @brief Size of the internal buffer used for string conversion.
diff --git a/src/yycc/rust/parse.hpp b/src/yycc/rust/num/parse.hpp
similarity index 87%
rename from src/yycc/rust/parse.hpp
rename to src/yycc/rust/num/parse.hpp
index 87e6215..6f2b65d 100644
--- a/src/yycc/rust/parse.hpp
+++ b/src/yycc/rust/num/parse.hpp
@@ -1,11 +1,11 @@
 #pragma once
-#include "../macro/feature_probe.hpp"
-#include "../string/parse.hpp"
-#include "panic.hpp"
-#include "result.hpp"
+#include "../../macro/feature_probe.hpp"
+#include "../../num/parse.hpp"
+#include "../panic.hpp"
+#include "../result.hpp"
 
 #define NS_YYCC_STRING ::yycc::string
-#define NS_YYCC_STRING_PARSE ::yycc::string::parse
+#define NS_YYCC_NUM_PARSE ::yycc::num::parse
 #define NS_YYCC_RUST_RESULT ::yycc::rust::result
 
 /**
@@ -15,12 +15,12 @@
  * This namespace contains template functions for parsing strings into different types
  * (floating-point, integral, boolean) with Rust-like Result error handling.
  */
-namespace yycc::rust::parse {
+namespace yycc::rust::num::parse {
 
 #if defined(YYCC_CPPFEAT_EXPECTED)
 
     /// @brief The error type of parsing.
-    using Error = NS_YYCC_STRING_PARSE::ParseError;
+    using Error = NS_YYCC_NUM_PARSE::ParseError;
 
     /// @brief The result type of parsing.
     /// @tparam T The expected value type in result.
@@ -37,7 +37,7 @@ namespace yycc::rust::parse {
     template<typename T, std::enable_if_t<std::is_floating_point_v<T>, int> = 0>
     Result<T> parse(const NS_YYCC_STRING::u8string_view& strl,
             std::chars_format fmt = std::chars_format::general) {
-        auto rv = NS_YYCC_STRING_PARSE::priv_parse<T>(strl, fmt);
+        auto rv = NS_YYCC_NUM_PARSE::priv_parse<T>(strl, fmt);
 
         if (const auto* ptr = std::get_if<T>(&rv)) {
             return NS_YYCC_RUST_RESULT::Ok<Result<T>>(*ptr);
@@ -58,7 +58,7 @@ namespace yycc::rust::parse {
      */
     template<typename T, std::enable_if_t<std::is_integral_v<T> && !std::is_same_v<T, bool>, int> = 0>
     Result<T> parse(const NS_YYCC_STRING::u8string_view& strl, int base = 10) {
-        auto rv = NS_YYCC_STRING_PARSE::priv_parse<T>(strl, base);
+        auto rv = NS_YYCC_NUM_PARSE::priv_parse<T>(strl, base);
 
         if (const auto* ptr = std::get_if<T>(&rv)) {
             return NS_YYCC_RUST_RESULT::Ok<Result<T>>(*ptr);
@@ -78,7 +78,7 @@ namespace yycc::rust::parse {
      */
     template<typename T, std::enable_if_t<std::is_same_v<T, bool>, int> = 0>
     Result<T> parse(const NS_YYCC_STRING::u8string_view& strl) {
-        auto rv = NS_YYCC_STRING_PARSE::priv_parse<T>(strl);
+        auto rv = NS_YYCC_NUM_PARSE::priv_parse<T>(strl);
 
         if (const auto* ptr = std::get_if<T>(&rv)) {
             return NS_YYCC_RUST_RESULT::Ok<Result<T>>(*ptr);
@@ -95,5 +95,5 @@ namespace yycc::rust::parse {
 }
 
 #undef NS_YYCC_RUST_RESULT
-#undef NS_YYCC_STRING_PARSE
+#undef NS_YYCC_NUM_PARSE
 #undef NS_YYCC_STRING
diff --git a/src/yycc/rust/stringify.hpp b/src/yycc/rust/num/stringify.hpp
similarity index 62%
rename from src/yycc/rust/stringify.hpp
rename to src/yycc/rust/num/stringify.hpp
index d360360..db7b199 100644
--- a/src/yycc/rust/stringify.hpp
+++ b/src/yycc/rust/num/stringify.hpp
@@ -1,10 +1,10 @@
 #pragma once
-#include "../string/stringify.hpp"
+#include "../../num/stringify.hpp"
 
-namespace yycc::rust::stringify {
+namespace yycc::rust::num::stringify {
 
     // There is no modification for legacy "stringify" functions like "parse".
     // So we simply expose all functions into this namespace.
-    using namespace ::yycc::string::stringify;
+    using namespace ::yycc::num::stringify;
 
 } // namespace yycc::rust::stringify
diff --git a/testbench/CMakeLists.txt b/testbench/CMakeLists.txt
index 8e5d410..6692174 100644
--- a/testbench/CMakeLists.txt
+++ b/testbench/CMakeLists.txt
@@ -8,10 +8,10 @@ PRIVATE
     yycc/constraint/builder.cpp
     yycc/string/op.cpp
     yycc/string/reinterpret.cpp
-    yycc/string/parse.cpp
-    yycc/string/stringify.cpp
-    yycc/rust/parse.cpp
-    yycc/rust/stringify.cpp
+    yycc/num/parse.cpp
+    yycc/num/stringify.cpp
+    yycc/rust/num/parse.cpp
+    yycc/rust/num/stringify.cpp
 )
 # Setup headers
 target_include_directories(YYCCTestbench
diff --git a/testbench/yycc/string/parse.cpp b/testbench/yycc/num/parse.cpp
similarity index 88%
rename from testbench/yycc/string/parse.cpp
rename to testbench/yycc/num/parse.cpp
index 75d1477..18631f6 100644
--- a/testbench/yycc/string/parse.cpp
+++ b/testbench/yycc/num/parse.cpp
@@ -1,13 +1,13 @@
 #include <gtest/gtest.h>
 #include <yycc.hpp>
-#include <yycc/string/parse.hpp>
+#include <yycc/num/parse.hpp>
 #include <yycc/string/reinterpret.hpp>
 
 #include <yycc/prelude/rust.hpp>
 
-#define PARSE ::yycc::string::parse
+#define PARSE ::yycc::num::parse
 
-namespace yycctest::string::parse {
+namespace yycctest::num::parse {
 
     // These 2 test macros build string container via given string.
     // Check `try_parse` first, and then check `parse`.
@@ -29,7 +29,7 @@ namespace yycctest::string::parse {
         EXPECT_ANY_THROW(PARSE::parse<type_t>(cache_string, ##__VA_ARGS__)); \
     }
 
-    TEST(StringParse, Common) {
+    TEST(NumParse, Common) {
         TEST_SUCCESS(i8, INT8_C(-61), "-61");
         TEST_SUCCESS(u8, UINT8_C(200), "200");
         TEST_SUCCESS(i16, INT16_C(6161), "6161");
@@ -46,17 +46,17 @@ namespace yycctest::string::parse {
         TEST_SUCCESS(bool, false, "false");
     }
 
-    TEST(StringParse, Radix) {
+    TEST(NumParse, Radix) {
         TEST_SUCCESS(u32, UINT32_C(0xffff), "ffff", 16);
         TEST_SUCCESS(u32, UINT32_C(032), "032", 8);
         TEST_SUCCESS(u32, UINT32_C(0B1011), "1011", 2);
     }
 
-    TEST(StringParse, CaseInsensitive) {
+    TEST(NumParse, CaseInsensitive) {
         TEST_SUCCESS(bool, true, "tRUE");
     }
 
-    TEST(StringParse, Overflow) {
+    TEST(NumParse, Overflow) {
         TEST_FAIL(i8, "6161");
         TEST_FAIL(u8, "32800");
         TEST_FAIL(i16, "61616161");
@@ -70,13 +70,13 @@ namespace yycctest::string::parse {
         TEST_FAIL(double, "1e114514");
     }
 
-    TEST(StringParse, BadRadix) {
+    TEST(NumParse, BadRadix) {
         TEST_FAIL(u32, "fghj", 16);
         TEST_FAIL(u32, "099", 8);
         TEST_FAIL(u32, "12345", 2);
     }
 
-    TEST(StringParse, InvalidWords) {
+    TEST(NumParse, InvalidWords) {
         TEST_FAIL(u32, "hello, world!");
         TEST_FAIL(bool, "hello, world!");
     }
diff --git a/testbench/yycc/string/stringify.cpp b/testbench/yycc/num/stringify.cpp
similarity index 86%
rename from testbench/yycc/string/stringify.cpp
rename to testbench/yycc/num/stringify.cpp
index fba5152..52850f6 100644
--- a/testbench/yycc/string/stringify.cpp
+++ b/testbench/yycc/num/stringify.cpp
@@ -1,13 +1,13 @@
 #include <gtest/gtest.h>
 #include <yycc.hpp>
+#include <yycc/num/stringify.hpp>
 #include <yycc/string/reinterpret.hpp>
-#include <yycc/string/stringify.hpp>
 
 #include <yycc/prelude/rust.hpp>
 
-#define STRINGIFY ::yycc::string::stringify
+#define STRINGIFY ::yycc::num::stringify
 
-namespace yycctest::string::stringify {
+namespace yycctest::num::stringify {
 
 #define TEST_SUCCESS(type_t, value, string_value, ...) \
     { \
@@ -16,7 +16,7 @@ namespace yycctest::string::stringify {
         EXPECT_EQ(ret, YYCC_U8(string_value)); \
     }
 
-    TEST(StringStringify, Common) {
+    TEST(NumStringify, Common) {
         TEST_SUCCESS(i8, INT8_C(-61), "-61");
         TEST_SUCCESS(u8, UINT8_C(200), "200");
         TEST_SUCCESS(i16, INT16_C(6161), "6161");
@@ -33,7 +33,7 @@ namespace yycctest::string::stringify {
         TEST_SUCCESS(bool, false, "false");
     }
 
-    TEST(StringStringify, Radix) {
+    TEST(NumStringify, Radix) {
         TEST_SUCCESS(u32, UINT32_C(0xffff), "ffff", 16);
         TEST_SUCCESS(u32, UINT32_C(032), "32", 8);
         TEST_SUCCESS(u32, UINT32_C(0B1011), "1011", 2);
diff --git a/testbench/yycc/rust/parse.cpp b/testbench/yycc/rust/num/parse.cpp
similarity index 89%
rename from testbench/yycc/rust/parse.cpp
rename to testbench/yycc/rust/num/parse.cpp
index 6d7f812..a90e0a6 100644
--- a/testbench/yycc/rust/parse.cpp
+++ b/testbench/yycc/rust/num/parse.cpp
@@ -1,10 +1,10 @@
 #include <gtest/gtest.h>
 #include <yycc.hpp>
-#include <yycc/rust/parse.hpp>
+#include <yycc/rust/num/parse.hpp>
 
 #include <yycc/prelude/rust.hpp>
 
-#define PARSE ::yycc::rust::parse
+#define PARSE ::yycc::rust::num::parse
 
 namespace yycctest::rust::parse {
 
@@ -30,7 +30,7 @@ namespace yycctest::rust::parse {
         EXPECT_FALSE(rv.has_value()); \
     }
 
-    TEST(RustParse, Common) {
+    TEST(RustNumParse, Common) {
         TEST_SUCCESS(i8, INT8_C(-61), "-61");
         TEST_SUCCESS(u8, UINT8_C(200), "200");
         TEST_SUCCESS(i16, INT16_C(6161), "6161");
@@ -47,17 +47,17 @@ namespace yycctest::rust::parse {
         TEST_SUCCESS(bool, false, "false");
     }
 
-    TEST(RustParse, Radix) {
+    TEST(RustNumParse, Radix) {
         TEST_SUCCESS(u32, UINT32_C(0xffff), "ffff", 16);
         TEST_SUCCESS(u32, UINT32_C(032), "032", 8);
         TEST_SUCCESS(u32, UINT32_C(0B1011), "1011", 2);
     }
 
-    TEST(RustParse, CaseInsensitive) {
+    TEST(RustNumParse, CaseInsensitive) {
         TEST_SUCCESS(bool, true, "tRUE");
     }
 
-    TEST(RustParse, Overflow) {
+    TEST(RustNumParse, Overflow) {
         TEST_FAIL(i8, "6161");
         TEST_FAIL(u8, "32800");
         TEST_FAIL(i16, "61616161");
@@ -71,13 +71,13 @@ namespace yycctest::rust::parse {
         TEST_FAIL(double, "1e114514");
     }
 
-    TEST(RustParse, BadRadix) {
+    TEST(RustNumParse, BadRadix) {
         TEST_FAIL(u32, "fghj", 16);
         TEST_FAIL(u32, "099", 8);
         TEST_FAIL(u32, "12345", 2);
     }
 
-    TEST(RustParse, InvalidWords) {
+    TEST(RustNumParse, InvalidWords) {
         TEST_FAIL(u32, "hello, world!");
         TEST_FAIL(bool, "hello, world!");
     }
diff --git a/testbench/yycc/rust/stringify.cpp b/testbench/yycc/rust/num/stringify.cpp
similarity index 88%
rename from testbench/yycc/rust/stringify.cpp
rename to testbench/yycc/rust/num/stringify.cpp
index d2d54c7..4452d7a 100644
--- a/testbench/yycc/rust/stringify.cpp
+++ b/testbench/yycc/rust/num/stringify.cpp
@@ -1,6 +1,6 @@
 #include <gtest/gtest.h>
 #include <yycc.hpp>
-#include <yycc/rust/stringify.hpp>
+#include <yycc/rust/num/stringify.hpp>
 
 #include <yycc/prelude/rust.hpp>