diff --git a/src/char_convert_loader.c b/src/char_convert_loader.c
index 69b8c1b..01be465 100644
--- a/src/char_convert_loader.c
+++ b/src/char_convert_loader.c
@@ -18,12 +18,18 @@
 
 int char_convert_loader_init(FastCharConverter *pCharConverter,
         const IniItem *items, const int count)
+{
+    char_convert_loader_init(pCharConverter, NULL, 0);
+    return char_convert_loader_add(pCharConverter, items, count);
+}
+
+int char_convert_loader_add(FastCharConverter *pCharConverter,
+        const IniItem *items, const int count)
 {
     const IniItem *pItem;
     const IniItem *pEnd;
     int result;
 
-    char_convert_loader_init(pCharConverter, NULL, 0);
     pEnd = items + count;
     for (pItem=items; pItem<pEnd; pItem++) {
         result = char_convert_loader_set_pair(pCharConverter,
diff --git a/src/char_convert_loader.h b/src/char_convert_loader.h
index b4900c1..ebffdd1 100644
--- a/src/char_convert_loader.h
+++ b/src/char_convert_loader.h
@@ -31,6 +31,17 @@ extern "C" {
 int char_convert_loader_init(FastCharConverter *pCharConverter,
         const IniItem *items, const int count);
 
+/**
+ *  char converter init function
+ *  parameters:
+ *           pCharConverter: the char converter
+ *           items: the char key value pairs
+ *           count: the count of kv pairs
+ *  return: 0 for success, != 0 fail
+*/
+int char_convert_loader_add(FastCharConverter *pCharConverter,
+        const IniItem *items, const int count);
+
 /**
  *  set char src and dest pair
  *  parameters:
diff --git a/src/char_converter.c b/src/char_converter.c
index badbf47..199d63a 100644
--- a/src/char_converter.c
+++ b/src/char_converter.c
@@ -15,8 +15,9 @@
 #include "shared_func.h"
 #include "char_converter.h"
 
-int char_converter_init(FastCharConverter *pCharConverter,
-        const FastCharPair *charPairs, const int count)
+int char_converter_init_ex(FastCharConverter *pCharConverter,
+        const FastCharPair *charPairs, const int count,
+        const unsigned op)
 {
     int i;
     unsigned char src;
@@ -33,7 +34,7 @@ int char_converter_init(FastCharConverter *pCharConverter,
     for (i=0; i<count; i++)
     {
         src = charPairs[i].src;
-        pCharConverter->char_table[src].op = FAST_CHAR_OP_NO_BACKSLASH;
+        pCharConverter->char_table[src].op = op;
         pCharConverter->char_table[src].dest = charPairs[i].dest;
     }
     return 0;
@@ -61,10 +62,28 @@ int std_space_char_converter_init(FastCharConverter *pCharConverter,
     return char_converter_init(pCharConverter, pairs, SPACE_CHAR_PAIR_COUNT);
 }
 
+int std_spaces_add_backslash_converter_init(FastCharConverter *pCharConverter)
+{
+#define SPACE_CHAR_PAIR_COUNT 7
+    FastCharPair pairs[SPACE_CHAR_PAIR_COUNT];
+
+    pairs[0].src = '\0'; pairs[0].dest = '0';
+    pairs[1].src = '\t'; pairs[1].dest = 't';
+    pairs[2].src = '\n'; pairs[2].dest = 'n';
+    pairs[3].src = '\v'; pairs[3].dest = 'v';
+    pairs[4].src = '\f'; pairs[4].dest = 'f';
+    pairs[5].src = '\r'; pairs[5].dest = 'r';
+    pairs[6].src = ' ';  pairs[6].dest = '-';
+
+    return char_converter_init_ex(pCharConverter, pairs,
+            SPACE_CHAR_PAIR_COUNT, FAST_CHAR_OP_ADD_BACKSLASH);
+}
+
 void char_converter_set_pair(FastCharConverter *pCharConverter,
         const unsigned char src, const unsigned char dest)
 {
-    char_converter_set_pair_ex(pCharConverter, src, FAST_CHAR_OP_NO_BACKSLASH, dest);
+    char_converter_set_pair_ex(pCharConverter, src,
+            FAST_CHAR_OP_NO_BACKSLASH, dest);
 }
 
 void char_converter_set_pair_ex(FastCharConverter *pCharConverter,
@@ -93,7 +112,6 @@ int fast_char_convert(FastCharConverter *pCharConverter,
     unsigned char *po;
     unsigned char *end;
     int out_size_sub1;
-    int remain_len;
 
     count = 0;
     po = (unsigned char *)output;
@@ -115,8 +133,7 @@ int fast_char_convert(FastCharConverter *pCharConverter,
         }
     }
 
-    remain_len = end - pi;
-    if (remain_len == 0) {
+    if (pi == end) {
         *out_len = po - (unsigned char *)output;
         return count;
     }
diff --git a/src/char_converter.h b/src/char_converter.h
index dd7742c..5ddec1f 100644
--- a/src/char_converter.h
+++ b/src/char_converter.h
@@ -55,10 +55,27 @@ typedef struct fast_char_converter
  *           pCharConverter: the char converter
  *           charPairs: the char pairs
  *           count: the count of char pairs
+ *           op: the operator type
  *  return: 0 for success, != 0 fail
 */
-int char_converter_init(FastCharConverter *pCharConverter,
-        const FastCharPair *charPairs, const int count);
+int char_converter_init_ex(FastCharConverter *pCharConverter,
+        const FastCharPair *charPairs, const int count,
+        const unsigned op);
+
+/**
+ *  char converter init function
+ *  parameters:
+ *           pCharConverter: the char converter
+ *           charPairs: the char pairs
+ *           count: the count of char pairs
+ *  return: 0 for success, != 0 fail
+*/
+static inline int char_converter_init(FastCharConverter *pCharConverter,
+        const FastCharPair *charPairs, const int count)
+{
+    return char_converter_init_ex(pCharConverter, charPairs, count,
+            FAST_CHAR_OP_NO_BACKSLASH);
+}
 
 /**
  *  standard space chars to convert
@@ -70,6 +87,14 @@ int char_converter_init(FastCharConverter *pCharConverter,
 int std_space_char_converter_init(FastCharConverter *pCharConverter,
         const unsigned char dest_base);
 
+/**
+ *  standard space chars init to add backslash
+ *  parameters:
+ *           pCharConverter: the char converter
+ *  return: 0 for success, != 0 fail
+*/
+int std_spaces_add_backslash_converter_init(FastCharConverter *pCharConverter);
+
 /**
  *  set char pair to converter
  *  parameters: