diff --git a/src/KeyWordExt.cpp b/src/KeyWordExt.cpp
index cd9c00d..0120954 100644
--- a/src/KeyWordExt.cpp
+++ b/src/KeyWordExt.cpp
@@ -149,7 +149,7 @@ namespace CppJieba
 
 	bool KeyWordExt::extract(const string& utf8Str, vector<string>& keywords, uint topN)
 	{
-		LogInfo(string_format("title:[%s]",utf8Str.c_str()));
+		LogDebug(string_format("title:[%s]",utf8Str.c_str()));
 
 		bool retFlag;
 		vector<string> words;
@@ -177,7 +177,7 @@ namespace CppJieba
 		}
 		//LogDebug("_extractTopN finished.");
 
-		LogInfo(string_format("ext res:[%s]", joinStr(keywords, ",").c_str()));
+		LogDebug(string_format("ext res:[%s]", joinStr(keywords, ",").c_str()));
 		return true;
 	}
 
diff --git a/src/cppcommon/str_functs.cpp b/src/cppcommon/str_functs.cpp
index afb677c..b0dd97b 100644
--- a/src/cppcommon/str_functs.cpp
+++ b/src/cppcommon/str_functs.cpp
@@ -331,14 +331,18 @@ namespace CPPCOMMON
 	string gbkToUtf8(const string& gbk)
 	{
 		//cout<<__FILE__<<__LINE__<<gbk<<endl;
-		string res;
+		if(gbk.empty())
+		{
+			return "";
+		}
+		string res("");
 		size_t maxLen = gbk.size()*4;
 		char * pUtf = new char[maxLen];
 		int ret = code_convert("gbk", "utf-8", (char *)gbk.c_str(), gbk.size(), pUtf, maxLen);
 		if(ret == -1)
 		{
 			delete [] pUtf;
-			return "";
+			return res;
 		}
 		res = pUtf;
 		delete [] pUtf;