diff --git a/TinySTL/Queue.h b/TinySTL/Queue.h
index c9d7388..8a6b782 100644
--- a/TinySTL/Queue.h
+++ b/TinySTL/Queue.h
@@ -2,6 +2,7 @@
 #define _QUEUE_H_
 
 #include "Deque.h"
+#include "Functional.h"
 #include "Vector.h"
 
 namespace TinySTL{
diff --git a/TinySTL/String.h b/TinySTL/String.h
index e598500..ff5ee9f 100644
--- a/TinySTL/String.h
+++ b/TinySTL/String.h
@@ -4,6 +4,7 @@
 #include "Allocator.h"
 #include "ReverseIterator.h"
 #include "UninitializedFunctions.h"
+#include "Utility.h"
 
 #include <cstring>
 #include <type_traits>
@@ -122,9 +123,9 @@ namespace TinySTL{
 		string& replace(iterator i1, iterator i2, InputIterator first, InputIterator last);
 
 		void swap(string& str){
-			std::swap(start_, str.start_);
-			std::swap(finish_, str.finish_);
-			std::swap(endOfStorage_, str.endOfStorage_);
+			TinySTL::swap(start_, str.start_);
+			TinySTL::swap(finish_, str.finish_);
+			TinySTL::swap(endOfStorage_, str.endOfStorage_);
 		}
 		size_t copy(char* s, size_t len, size_t pos = 0) const{
 			auto ptr = TinySTL::uninitialized_copy(begin() + pos, begin() + pos + len, s);
diff --git a/TinySTL/TinySTL.vcxproj b/TinySTL/TinySTL.vcxproj
index eb56b30..28ffe5d 100644
--- a/TinySTL/TinySTL.vcxproj
+++ b/TinySTL/TinySTL.vcxproj
@@ -99,6 +99,7 @@
     <ClInclude Include="String.h" />
     <ClInclude Include="TypeTraits.h" />
     <ClInclude Include="UninitializedFunctions.h" />
+    <ClInclude Include="Utility.h" />
     <ClInclude Include="Vector.h" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
diff --git a/TinySTL/TinySTL.vcxproj.filters b/TinySTL/TinySTL.vcxproj.filters
index e5fb7a4..ea8ac16 100644
--- a/TinySTL/TinySTL.vcxproj.filters
+++ b/TinySTL/TinySTL.vcxproj.filters
@@ -77,5 +77,8 @@
     <ClInclude Include="Functional.h">
       <Filter>头文件</Filter>
     </ClInclude>
+    <ClInclude Include="Utility.h">
+      <Filter>头文件</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/TinySTL/Utility.h b/TinySTL/Utility.h
new file mode 100644
index 0000000..1446094
--- /dev/null
+++ b/TinySTL/Utility.h
@@ -0,0 +1,13 @@
+#ifndef _UTILITY_H_
+#define _UTILITY_H_
+
+namespace TinySTL{
+	//************ [swap] ***************
+	template<class T>
+	void swap(T& a, T& b){
+		T temp = a;
+		a = b;
+		b = temp;
+	}
+}
+#endif
\ No newline at end of file