diff --git a/src/sorted_array.c b/src/sorted_array.c
index 7d32d45..b3ea85f 100644
--- a/src/sorted_array.c
+++ b/src/sorted_array.c
@@ -108,6 +108,21 @@ int sorted_array_insert(SortedArrayContext *ctx,
     return 0;
 }
 
+void sorted_array_delete_by_index(SortedArrayContext *ctx,
+        void *base, int *count, const int index)
+{
+    int move_count;
+    char *start;
+
+    start = (char *)base + ctx->element_size * index;
+    move_count = *count - (index + 1);
+    if (move_count > 0) {
+        memmove(start, start + ctx->element_size,
+                ctx->element_size * move_count);
+    }
+    (*count)--;
+}
+
 int sorted_array_delete(SortedArrayContext *ctx,
         void *base, int *count, const void *elt)
 {
diff --git a/src/sorted_array.h b/src/sorted_array.h
index beb6e4f..c9f2e74 100644
--- a/src/sorted_array.h
+++ b/src/sorted_array.h
@@ -65,6 +65,16 @@ extern "C" {
     int sorted_array_delete(SortedArrayContext *ctx,
             void *base, int *count, const void *elt);
 
+    /** delete an element by index
+     *  parameters:
+     *      ctx: the context for sorted array
+     *      base: the pointer of the sorted array (the first array element)
+     *      count: the count of the sorted array (for input and output)
+     *      index: the element index to delete
+     *  return: 0 for success, != 0 for error
+     */
+    void sorted_array_delete_by_index(SortedArrayContext *ctx,
+            void *base, int *count, const int index);
 
     /** find element from the sorted array
      *  parameters: