3.0.0, code review

Author: Demonese

README.ZH.md

@@ -16,12 +16,12 @@
 
 ```c++
 #include <iostream>
-#include <encoding/string.hpp>
+#include <ext/string.hpp>
 
 using std::string_view_literals::operator""sv;
 
 int main() {
-  std::wcout << encoding::to_wstring("Hello world!"sv) << std::endl;
+  std::wcout << ext::to_wstring("Hello world!"sv) << std::endl;
   return 0;
 }
 ```
@@ -30,7 +30,7 @@ int main() {
 
 ```c++
 #define PAINFUL_CPP_STRING_CONVERSION_NAMESPACE foo
-#include <encoding/string.hpp>
+#include <ext/string.hpp>
 ```
 
 ## 互转表格

README.md

@@ -16,12 +16,12 @@ You can convert strings through the following API:
 
 ```c++
 #include <iostream>
-#include <encoding/string.hpp>
+#include <ext/string.hpp>
 
 using std::string_view_literals::operator""sv;
 
 int main() {
-  std::wcout << encoding::to_wstring("Hello world!"sv) << std::endl;
+  std::wcout << ext::to_wstring("Hello world!"sv) << std::endl;
   return 0;
 }
 ```
@@ -30,7 +30,7 @@ You can customize namespace:
 
 ```c++
 #define PAINFUL_CPP_STRING_CONVERSION_NAMESPACE foo
-#include <encoding/string.hpp>
+#include <ext/string.hpp>
 ```
 
 ## Conversion matrix

include/ext/string.hpp

@@ -3,8 +3,8 @@
 // Author: 璀境石 (GitHub: @Demonese / @chuikingshek)
 #pragma once
 
-#ifndef PAINFUL_CPP_STRING_CONVERSION_ENCODING_STRING_H
-#define PAINFUL_CPP_STRING_CONVERSION_ENCODING_STRING_H
+#ifndef PAINFUL_CPP_STRING_CONVERSION_EXT_STRING_H
+#define PAINFUL_CPP_STRING_CONVERSION_EXT_STRING_H
 
 #ifndef PAINFUL_CPP_STRING_CONVERSION_NAMESPACE
 #define PAINFUL_CPP_STRING_CONVERSION_NAMESPACE ext

include/ext/string_view.hpp

@@ -3,8 +3,8 @@
 // Author: 璀境石 (GitHub: @Demonese / @chuikingshek)
 #pragma once
 
-#ifndef PAINFUL_CPP_STRING_CONVERSION_ENCODING_STRING_VIEW_H
-#define PAINFUL_CPP_STRING_CONVERSION_ENCODING_STRING_VIEW_H
+#ifndef PAINFUL_CPP_STRING_CONVERSION_EXT_STRING_VIEW_H
+#define PAINFUL_CPP_STRING_CONVERSION_EXT_STRING_VIEW_H
 
 #ifndef PAINFUL_CPP_STRING_CONVERSION_NAMESPACE
 #define PAINFUL_CPP_STRING_CONVERSION_NAMESPACE ext