diff --git a/src/FullSegment.hpp b/src/FullSegment.hpp
index 91c5fdc..d67f2f3 100644
--- a/src/FullSegment.hpp
+++ b/src/FullSegment.hpp
@@ -3,6 +3,7 @@
 
 #include <algorithm>
 #include <set>
+#include <cassert>
 #include "Limonp/logger.hpp"
 #include "Trie.hpp"
 #include "ISegment.hpp"
@@ -63,15 +64,16 @@ namespace CppJieba
     public:
         bool cut(Unicode::const_iterator begin, Unicode::const_iterator end, vector<Unicode>& res) const
         {
+            assert(_getInitFlag());
 #ifndef NO_CODING_LOG
-            if (!_getInitFlag())
+            //if (!_getInitFlag())
+            //{
+            //    LogError("not inited.");
+            //    return false;
+            //}
+            if (begin >= end)
             {
-                LogError("not inited.");
-                return false;
-            }
-            if (begin > end)
-            {
-                LogError("begin > end");
+                LogError("begin >= end");
                 return false;
             }
 #endif
diff --git a/src/HMMSegment.hpp b/src/HMMSegment.hpp
index c9839a4..6e2b7b7 100644
--- a/src/HMMSegment.hpp
+++ b/src/HMMSegment.hpp
@@ -4,6 +4,7 @@
 #include <iostream>
 #include <fstream>
 #include <memory.h>
+#include <cassert>
 #include "Limonp/str_functs.hpp"
 #include "Limonp/logger.hpp"
 #include "TransCode.hpp"
@@ -93,11 +94,12 @@ namespace CppJieba
         public:
             virtual bool cut(Unicode::const_iterator begin, Unicode::const_iterator end, vector<string>& res)const
             {
-                if(!_getInitFlag())
-                {
-                    LogError("not inited.");
-                    return false;
-                }
+                //if(!_getInitFlag())
+                //{
+                //    LogError("not inited.");
+                //    return false;
+                //}
+                assert(_getInitFlag());
                 if(begin == end)
                 {
                     return false;
diff --git a/src/MPSegment.hpp b/src/MPSegment.hpp
index 09d10b5..14b8f21 100644
--- a/src/MPSegment.hpp
+++ b/src/MPSegment.hpp
@@ -7,6 +7,7 @@
 
 #include <algorithm>
 #include <set>
+#include <cassert>
 #include "Limonp/logger.hpp"
 #include "Trie.hpp"
 #include "ISegment.hpp"
@@ -73,11 +74,13 @@ namespace CppJieba
         public:
             virtual bool cut(Unicode::const_iterator begin, Unicode::const_iterator end, vector<string>& res)const
             {
-                if(!_getInitFlag())
-                {
-                    LogError("not inited.");
-                    return false;
-                }
+                //if(!_getInitFlag())
+                //{
+                //    LogError("not inited.");
+                //    return false;
+                //}
+                assert(_getInitFlag());
+
                 vector<TrieNodeInfo> segWordInfos;
                 if(!cut(begin, end, segWordInfos))
                 {
diff --git a/src/MixSegment.hpp b/src/MixSegment.hpp
index 8914256..5f35031 100644
--- a/src/MixSegment.hpp
+++ b/src/MixSegment.hpp
@@ -1,6 +1,7 @@
 #ifndef CPPJIEBA_MIXSEGMENT_H
 #define CPPJIEBA_MIXSEGMENT_H
 
+#include <cassert>
 #include "MPSegment.hpp"
 #include "HMMSegment.hpp"
 #include "Limonp/str_functs.hpp"
@@ -56,11 +57,12 @@ namespace CppJieba
         public:
             virtual bool cut(Unicode::const_iterator begin, Unicode::const_iterator end, vector<string>& res)const
             {
-                if(!_getInitFlag())
-                {
-                    LogError("not inited.");
-                    return false;
-                }
+                //if(!_getInitFlag())
+                //{
+                //    LogError("not inited.");
+                //    return false;
+                //}
+                assert(_getInitFlag());
                 if(begin == end)
                 {
                     return false;
diff --git a/src/QuerySegment.hpp b/src/QuerySegment.hpp
index 58cf1a2..4487339 100644
--- a/src/QuerySegment.hpp
+++ b/src/QuerySegment.hpp
@@ -3,6 +3,7 @@
 
 #include <algorithm>
 #include <set>
+#include <cassert>
 #include "Limonp/logger.hpp"
 #include "Trie.hpp"
 #include "ISegment.hpp"
@@ -64,15 +65,16 @@ namespace CppJieba
     public:
         bool cut(Unicode::const_iterator begin, Unicode::const_iterator end, vector<Unicode>& res) const
         {
+            assert(_getInitFlag());
 #ifndef NO_CODING_LOG
-            if (!_getInitFlag())
+            //if (!_getInitFlag())
+            //{
+            //    LogError("not inited.");
+            //    return false;
+            //}
+            if (begin >= end)
             {
-                LogError("not inited.");
-                return false;
-            }
-            if (begin > end)
-            {
-                LogError("begin > end");
+                LogError("begin >= end");
                 return false;
             }
 #endif