diff --git a/src/cppcommon/Makefile b/src/cppcommon/Makefile
index cb2d2cf..af18990 100644
--- a/src/cppcommon/Makefile
+++ b/src/cppcommon/Makefile
@@ -29,6 +29,8 @@ io_functs.test: io_functs.cpp io_functs.h
 	g++ -o $@ $< -DTEST_IO_FUNCTS
 str_functs.ut: str_functs.cpp str_functs.h
 	g++ -o $@ $< -DTEST_STR_FUNCTS -liconv
+encoding.ut: encoding.cpp str_functs.cpp str_functs.h encoding.h
+	g++ -o $@ encoding.cpp str_functs.cpp -DENCODING_UT -liconv
 vec_functs.test: vec_functs.cpp vec_functs.h vec_functs.tcc
 	g++ -o $@ $< -DTEST_VEC_FUNCTS
 
diff --git a/src/cppcommon/str_functs.cpp b/src/cppcommon/str_functs.cpp
index 4394206..4c6456a 100644
--- a/src/cppcommon/str_functs.cpp
+++ b/src/cppcommon/str_functs.cpp
@@ -452,6 +452,8 @@ int main()
 		string utfStr = unicodeToUtf8(uniStr);
 		cout<<utfStr<<endl;
 	}
+	cout<<utf8ToGbk("")<<endl;
+	cout<<gbkToUtf8("")<<endl;
 	//vector<string> tmp;
 	//tmp.push_back("1");
 	////tmp.push_back("2");
diff --git a/src/cppcommon/testdata/dict.gbk b/src/cppcommon/testdata/dict.gbk
index ac9f336..0fde7e6 100644
--- a/src/cppcommon/testdata/dict.gbk
+++ b/src/cppcommon/testdata/dict.gbk
@@ -2,6 +2,7 @@ AT&T 3 nz
 B�� 3 n
 c# 3 nz
 C# 3 nz
+
 c++ 3 nz
 C++ 3 nz
 T�� 4 n
diff --git a/src/cppcommon/testdata/dict.utf8 b/src/cppcommon/testdata/dict.utf8
index c44839b..cc0ace2 100644
--- a/src/cppcommon/testdata/dict.utf8
+++ b/src/cppcommon/testdata/dict.utf8
@@ -1,5 +1,6 @@
 包邮拉菲草18cm大檐进口草帽子超强遮阳防晒欧美日韩新款夏天 女
 AT&T 3 nz
+
 B超 3 n
 c# 3 nz
 C# 3 nz