diff --git a/version2.0/main.cpp b/version2.0/main.cpp
index be9770c..ccb8f23 100644
--- a/version2.0/main.cpp
+++ b/version2.0/main.cpp
@@ -3,6 +3,9 @@
 resource_file resource;
 nasal_lexer lexer;
 nasal_parse parser;
+abstract_syntax_tree libroot;
+abstract_syntax_tree root;
+
 nasal_symbol_table symtable;
 
 std::string command;
@@ -10,13 +13,13 @@ std::string command;
 int main()
 {
 #ifdef _WIN32
-			std::cout<<">>[system] Windows system."<<std::endl;
+			std::cout<<">> [system] Windows system."<<std::endl;
 #endif
 #ifdef _linux_
-			std::cout<<">>[system] Linux system."<<std::endl;
+			std::cout<<">> [system] Linux system."<<std::endl;
 #endif
 #ifdef TARGET_OS_MAC
-			std::cout<<">>[system] MacOS system."<<std::endl;
+			std::cout<<">> [system] MacOS system."<<std::endl;
 #endif
 	std::cout<<">> Nasal interpreter ver 2.0 ."<<std::endl;
 	std::cout<<">> Code: https://github.com/ValKmjolnir/Nasal-Interpreter"<<std::endl;
@@ -33,7 +36,6 @@ int main()
 			std::cout<<">> [del   ] clear the resource code."<<std::endl;
 			std::cout<<">> [lib   ] add lib file."<<std::endl;
 			std::cout<<">> [rs    ] print resource code."<<std::endl;
-			std::cout<<">> [total ] print resource code with lib code."<<std::endl;
 			std::cout<<">> [lex   ] turn code into tokens."<<std::endl;
 			std::cout<<">> [par   ] turn tokens into abstract syntax tree."<<std::endl;
 			std::cout<<">> [ast   ] check the abstract syntax tree."<<std::endl;
@@ -60,20 +62,37 @@ int main()
 			lexer.delete_all_tokens();
 			parser.delete_all_elements();
 			symtable.set_scope_clear();
-			std::cout<<">>[Delete] complete."<<std::endl;
+			root.set_clear();
+			std::cout<<">> [Delete] complete."<<std::endl;
 		}
 		else if(command=="lib")
 		{
+			libroot.set_clear();
 			resource.load_lib_file();
-			std::cout<<">>[Lib] loaded."<<std::endl;
+			lexer.scanner(resource.get_source());
+			lexer.generate_detail_token();
+			if(!lexer.get_error())
+			{
+				parser.get_token_list(lexer.get_detail_token_list());
+				parser.main_generate();
+				if(!parser.get_error())
+				{
+					libroot=parser.get_root();
+					std::cout<<">> [Lib] loaded."<<std::endl;
+				}
+				else
+					std::cout<<">> [Lib-error] lib files have parse error(s),stop."<<std::endl;
+			}
+			else
+				std::cout<<">> [Lib-error] lib files have lexer error(s),stop."<<std::endl;
+			resource.delete_all_source();
+			lexer.delete_all_tokens();
+			parser.delete_all_elements();
+			symtable.set_scope_clear();
 		}
 		else if(command=="rs")
 		{
-			resource.print_resource(false);
-		}
-		else if(command=="total")
-		{
-			resource.print_resource(true);
+			resource.print_resource();
 		}
 		else if(command=="lex")
 		{
@@ -82,7 +101,7 @@ int main()
 			if(!lexer.get_error())
 				lexer.print_token_list();
 			else
-				std::cout<<">>[Lexer] error occurred,stop."<<std::endl;
+				std::cout<<">> [Lexer] error occurred,stop."<<std::endl;
 		}
 		else if(command=="par")
 		{
@@ -95,7 +114,7 @@ int main()
 				parser.main_generate();
 			}
 			else
-				std::cout<<">>[Lexer] error occurred,stop."<<std::endl;
+				std::cout<<">> [Lexer] error occurred,stop."<<std::endl;
 		}
 		else if(command=="ast")
 		{
@@ -109,13 +128,13 @@ int main()
 				{
 					symtable.set_scope_clear();
 					symtable.symbol_table_main_generate(parser.get_root());
-					parser.get_root().print_tree(1);
+					parser.get_root().print_tree();
 				}
 				else
-					std::cout<<">>[Parse] error occurred,stop."<<std::endl;
+					std::cout<<">> [Parse] error occurred,stop."<<std::endl;
 			}
 			else
-				std::cout<<">>[Lexer] error occurred,stop."<<std::endl;
+				std::cout<<">> [Lexer] error occurred,stop."<<std::endl;
 		}
 		else if(command=="sym")
 		{
@@ -131,13 +150,13 @@ int main()
 					symtable.symbol_table_main_generate(parser.get_root());
 					symtable.print_symbol_table();
 					if(symtable.get_error())
-						std::cout<<">>[Symbol] error occurred,stop."<<std::endl;
+						std::cout<<">> [Symbol] error occurred,stop."<<std::endl;
 				}
 				else
-					std::cout<<">>[Parse] error occurred,stop."<<std::endl;
+					std::cout<<">> [Parse] error occurred,stop."<<std::endl;
 			}
 			else
-				std::cout<<">>[Lexer] error occurred,stop."<<std::endl;
+				std::cout<<">> [Lexer] error occurred,stop."<<std::endl;
 		}
 		else if(command=="run")
 		{
@@ -152,15 +171,15 @@ int main()
 					symtable.set_scope_clear();
 					symtable.symbol_table_main_generate(parser.get_root());
 					if(!symtable.get_error())
-						;// run code
+						root=parser.get_root();// run code
 					else
-						std::cout<<">>[Symbol] error occurred,stop."<<std::endl;
+						std::cout<<">> [Symbol] error occurred,stop."<<std::endl;
 				}
 				else
-					std::cout<<">>[Parse] error occurred,stop."<<std::endl;
+					std::cout<<">> [Parse] error occurred,stop."<<std::endl;
 			}
 			else
-				std::cout<<">>[Lexer] error occurred,stop."<<std::endl;
+				std::cout<<">> [Lexer] error occurred,stop."<<std::endl;
 		}
 		else if(command=="info")
 		{
@@ -170,7 +189,7 @@ int main()
 			parser.get_token_list(lexer.get_detail_token_list());
 			parser.print_detail_token();
 			parser.main_generate();
-			parser.get_root().print_tree(1);
+			parser.get_root().print_tree();
 		}
 		else if(command=="exit")
 			break;
diff --git a/version2.0/nasal_enum.h b/version2.0/nasal_enum.h
index 3e14869..31a3e87 100644
--- a/version2.0/nasal_enum.h
+++ b/version2.0/nasal_enum.h
@@ -62,7 +62,6 @@ enum parse_token_type
 	__definition,
 	__function,__conditional
 };
-
 void print_parse_token(int type)
 {
 	std::string context="";
@@ -189,10 +188,9 @@ enum parse_error_type
 
 	ternary_operator_lack_colon, // lack ':'
 };
-
 void print_parse_error(int error_type,int line,int error_token_type=__stack_end)
 {
-	std::string error_info_head=">>[Parse-error] line ";
+	std::string error_info_head=">> [Parse-error] line ";
 	std::string warning_info_head=">> [Parse-warning] line ";
 	switch(error_type)
 	{
@@ -313,4 +311,29 @@ void print_parse_error(int error_type,int line,int error_token_type=__stack_end)
 	return;
 }
 
+enum scalar_type
+{
+	scalar_nil,
+	scalar_number=1,
+	scalar_string,
+	scalar_vector,
+	scalar_hash,
+	scalar_function
+};
+void print_scalar_type(const int type)
+{
+	switch(type)
+	{
+		case scalar_nil:      std::cout<<"nil";break;
+		case scalar_number:
+		case scalar_string:   std::cout<<"scalar";break;
+		case scalar_vector:   std::cout<<"vector";break;
+		case scalar_hash:     std::cout<<"hash";break;
+		case scalar_function: std::cout<<"function";break;
+		default:              std::cout<<"nil";break;
+	}
+	return;
+}
+
+
 #endif
diff --git a/version2.0/nasal_lexer.h b/version2.0/nasal_lexer.h
index 27704ef..0a4944e 100644
--- a/version2.0/nasal_lexer.h
+++ b/version2.0/nasal_lexer.h
@@ -32,6 +32,19 @@
 		others: __unknown_operator
 */
 
+const std::string lib_filename[9]=
+{
+	"lib/base.nas",
+	"lib/bits.nas",
+	"lib/io.nas",
+	"lib/math.nas",
+	"lib/readline.nas",
+	"lib/sqlite.nas",
+	"lib/thread.nas",
+	"lib/unix.nas",
+	"lib/utf8.nas"
+};
+
 std::string reserve_word[15]=
 {
 	"for","foreach","forindex","while",
@@ -50,9 +63,7 @@ int is_reserve_word(std::string str)
 class resource_file
 {
 	private:
-		std::list<char> libsource;
 		std::list<char> resource;
-		std::list<char> totalcode;
 	public:
 		/*
 		resource_file();
@@ -61,27 +72,21 @@ class resource_file
 		void input_file(std::string);
 		void load_lib_file();
 		std::list<char>& get_source();
-		void print_resource(bool);
+		void print_resource();
 		*/
 		resource_file()
 		{
-			libsource.clear();
 			resource.clear();
-			totalcode.clear();
 			return;
 		}
 		~resource_file()
 		{
-			libsource.clear();
 			resource.clear();
-			totalcode.clear();
 			return;
 		}
 		void delete_all_source()
 		{
-			libsource.clear();
 			resource.clear();
-			totalcode.clear();
 			return;
 		}
 		void input_file(std::string filename)
@@ -90,7 +95,7 @@ class resource_file
 			std::ifstream fin(filename,std::ios::binary);
 			if(fin.fail())
 			{
-				std::cout<<">>[Resource] cannot open file \'"<<filename<<"\' ."<<std::endl;
+				std::cout<<">> [Resource] cannot open file \'"<<filename<<"\' ."<<std::endl;
 				fin.close();
 				return;
 			}
@@ -106,33 +111,36 @@ class resource_file
 		}
 		void load_lib_file()
 		{
-			libsource.clear();
-			/*
-			ifstream lib files here
-			*/
+			resource.clear();
+			for(int i=0;i<9;++i)
+			{
+				std::ifstream fin(lib_filename[i],std::ios::binary);
+				if(fin.fail())
+					std::cout<<">> [Resource] fatal error: lack \'"<<lib_filename[i]<<"\'"<<std::endl;
+				else
+				{
+					char c=0;
+					while(!fin.eof())
+					{
+						c=fin.get();
+						if(fin.eof())
+							break;
+						resource.push_back(c);
+					}
+				}
+				fin.close();
+			}
 			return;
 		}
 		std::list<char>& get_source()
 		{
-			totalcode.clear();
-			for(std::list<char>::iterator i=libsource.begin();i!=libsource.end();++i)
-				totalcode.push_back(*i);
-			for(std::list<char>::iterator i=resource.begin();i!=resource.end();++i)
-				totalcode.push_back(*i);
-			return totalcode;
+			return resource;
 		}
-		void print_resource(bool withlib)
+		void print_resource()
 		{
-			std::list<char> tmp;
-			if(withlib)
-				for(std::list<char>::iterator i=libsource.begin();i!=libsource.end();++i)
-					tmp.push_back(*i);
-			for(std::list<char>::iterator i=resource.begin();i!=resource.end();++i)
-				tmp.push_back(*i);
-			
 			int line=1;
 			std::cout<<line<<"\t";
-			for(std::list<char>::iterator i=tmp.begin();i!=tmp.end();++i)
+			for(std::list<char>::iterator i=resource.begin();i!=resource.end();++i)
 			{
 				if(32<=*i)
 					std::cout<<*i;
@@ -282,7 +290,7 @@ class nasal_lexer
 					if(!check_numerable_string(token_str))
 					{
 						++error;
-						std::cout<<">>[Lexer-error] line "<<line<<": "<<token_str<<" is not a numerable string."<<std::endl;
+						std::cout<<">> [Lexer-error] line "<<line<<": "<<token_str<<" is not a numerable string."<<std::endl;
 						token_str="0";
 					}
 					token new_token;
@@ -333,7 +341,7 @@ class nasal_lexer
 					if(ptr==res.end() || *ptr!=str_begin)
 					{
 						++error;
-						std::cout<<">>[Lexer-error] line "<<line<<": this string must have a \' "<<str_begin<<" \' as its end."<<std::endl;
+						std::cout<<">> [Lexer-error] line "<<line<<": this string must have a \' "<<str_begin<<" \' as its end."<<std::endl;
 						--ptr;
 					}
 					else
@@ -378,11 +386,11 @@ class nasal_lexer
 				else
 				{
 					++error;
-					std::cout<<">>[Lexer-error] line "<<line<<": unknown char."<<std::endl;
+					std::cout<<">> [Lexer-error] line "<<line<<": unknown char."<<std::endl;
 					++ptr;
 				}
 			}
-			std::cout<<">>[Pre-lexer] complete scanning. "<<error<<" error(s)."<<std::endl;
+			std::cout<<">> [Pre-lexer] complete scanning. "<<error<<" error(s)."<<std::endl;
 			return;
 		}
 		void generate_detail_token()
@@ -484,13 +492,13 @@ class nasal_lexer
 					else
 					{
 						++error;
-						std::cout<<">>[Lexer-error] line "<<detail_token.line<<": unknown operator \'"<<i->str<<"\'."<<std::endl;
+						std::cout<<">> [Lexer-error] line "<<detail_token.line<<": unknown operator \'"<<i->str<<"\'."<<std::endl;
 						detail_token.type=__unknown_operator;
 					}
 					detail_token_list.push_back(detail_token);
 				}
 			}
-			std::cout<<">>[Detail-lexer] complete generating. "<<error<<" error(s)."<<std::endl;
+			std::cout<<">> [Detail-lexer] complete generating. "<<error<<" error(s)."<<std::endl;
 			return;
 		}
 		int get_error()
diff --git a/version2.0/nasal_parse.h b/version2.0/nasal_parse.h
index e66a043..b0ad64c 100644
--- a/version2.0/nasal_parse.h
+++ b/version2.0/nasal_parse.h
@@ -175,7 +175,6 @@ int nasal_parse::get_error()
 
 abstract_syntax_tree& nasal_parse::get_root()
 {
-	std::cout<<">>[Parse] output root address: "<<(&root)<<" ."<<std::endl;
 	return root;
 }
 
@@ -390,7 +389,7 @@ void nasal_parse::main_generate()
 		if(need_semi_check)
 			check_semi();
 	}
-	std::cout<<">>[Parse] complete generation. "<<error<<" error(s)."<<std::endl;
+	std::cout<<">> [Parse] complete generation. "<<error<<" error(s)."<<std::endl;
 	return;
 }
 
@@ -1430,7 +1429,12 @@ abstract_syntax_tree nasal_parse::loop_expr()
 		}
 		this->get_token();
 		if(this_token.type==__semi)
+		{
+			abstract_syntax_tree null_node;
+			null_node.set_node_type(__null_type);
+			loop_main_node.add_children(null_node);
 			this->push_token();
+		}
 		else
 		{
 			if(this_token.type==__var)
@@ -1443,7 +1447,7 @@ abstract_syntax_tree nasal_parse::loop_expr()
 				this->push_token();
 				// cannot use calculation() here
 				// because for-loop's first statement must be definition or call_identifier
-				loop_main_node.add_children(scalar_generate());
+				loop_main_node.add_children(calculation());
 			}
 		}
 		this->get_token();
@@ -1454,7 +1458,12 @@ abstract_syntax_tree nasal_parse::loop_expr()
 		}
 		this->get_token();
 		if(this_token.type==__semi)
+		{
+			abstract_syntax_tree null_node;
+			null_node.set_node_type(__null_type);
+			loop_main_node.add_children(null_node);
 			this->push_token();
+		}
 		else
 		{
 			this->push_token();
@@ -1468,7 +1477,12 @@ abstract_syntax_tree nasal_parse::loop_expr()
 		}
 		this->get_token();
 		if(this_token.type==__right_curve)
+		{
+			abstract_syntax_tree null_node;
+			null_node.set_node_type(__null_type);
+			loop_main_node.add_children(null_node);
 			this->push_token();
+		}
 		else
 		{
 			this->push_token();
diff --git a/version2.0/nasal_scalar.h b/version2.0/nasal_scalar.h
new file mode 100644
index 0000000..ab9c967
--- /dev/null
+++ b/version2.0/nasal_scalar.h
@@ -0,0 +1,70 @@
+#ifndef __NASAL_SCALAR_H__
+#define __NASAL_SCALAR_H__
+
+class nasal_scalar
+{
+	private:
+		int type;
+		std::string var_string;
+		double var_number;
+		std::vector<nasal_scalar> var_array;
+		std::map<std::string,nasal_scalar> var_hash;
+	public:
+		nasal_scalar()
+		{
+			type=scalar_nil;
+			var_string="";
+			var_number=0;
+			var_array.clear();
+			var_hash.clear();
+			return;
+		}
+		nasal_scalar(const nasal_scalar& tmp)
+		{
+			type=tmp.type;
+			var_string=tmp.var_string;
+			var_number=tmp.var_number;
+			var_array=tmp.var_array;
+			var_hash=tmp.var_hash;
+			return;
+		}
+		nasal_scalar& operator=(const nasal_scalar& tmp)
+		{
+			type=tmp.type;
+			var_string=tmp.var_string;
+			var_number=tmp.var_number;
+			var_array=tmp.var_array;
+			var_hash=tmp.var_hash;
+			return *this;
+		}
+		void set_clear()
+		{
+			type=scalar_nil;
+			var_string.clear();
+			var_number=0;
+			var_array.clear();
+			var_hash.clear();
+			return;
+		}
+		void set_type(const int tmp_type)
+		{
+			// scalar_function is the last enum in enum::scalar_type
+			type=tmp_type>scalar_function? scalar_nil:tmp_type;
+			return;
+		}
+		void set_number(const double tmp_number)
+		{
+			var_number=tmp_number;
+			return;
+		}
+		void set_string(const std::string& tmp_str)
+		{
+			var_string=tmp_str;
+			return;
+		}
+		int get_type()          {return type;}
+		double get_number()     {return var_number;}
+		std::string get_string(){return var_string;}
+};
+
+#endif
diff --git a/version2.0/nasal_symbol_table.h b/version2.0/nasal_symbol_table.h
index d5dac94..a30611e 100644
--- a/version2.0/nasal_symbol_table.h
+++ b/version2.0/nasal_symbol_table.h
@@ -33,6 +33,8 @@ class nasal_symbol_table
 {
     private:
         int error;
+        int global_number;
+        int local_number;
         std::list<symbol_table_unit> global_symbol_dictionary;// used to save symbols appeared in global scope
         std::list<symbol_table_unit> local_symbol_dictionary; // used to save symbols appeared in local scopes
         std::list<symbol_table_unit> global_scope;            // global scope
@@ -43,6 +45,7 @@ class nasal_symbol_table
         void local_list_del_scope();
         void local_scope_add_symbol(symbol_table_unit);
         int search_symbol_id(symbol_table_unit);
+        bool search_scope(symbol_table_unit);
     public:
         nasal_symbol_table();
         ~nasal_symbol_table();
@@ -55,6 +58,8 @@ class nasal_symbol_table
 nasal_symbol_table::nasal_symbol_table()
 {
     error=0;
+    global_number=0;
+    local_number=0;
     global_symbol_dictionary.clear();
     global_scope.clear();
     local_symbol_dictionary.clear();
@@ -65,6 +70,8 @@ nasal_symbol_table::nasal_symbol_table()
 nasal_symbol_table::~nasal_symbol_table()
 {
     error=0;
+    global_number=0;
+    local_number=0;
     global_symbol_dictionary.clear();
     global_scope.clear();
     local_symbol_dictionary.clear();
@@ -75,6 +82,8 @@ nasal_symbol_table::~nasal_symbol_table()
 void nasal_symbol_table::set_scope_clear()
 {
     error=0;
+    global_number=0;
+    local_number=0;
     global_symbol_dictionary.clear();
     global_scope.clear();
     local_symbol_dictionary.clear();
@@ -86,12 +95,12 @@ void nasal_symbol_table::print_symbol_table()
 {
     if(!global_symbol_dictionary.empty())
     {
-        std::cout<<">>[Symbol] global scope:"<<std::endl;
+        std::cout<<">> [Symbol] global scope:"<<std::endl;
         for(std::list<symbol_table_unit>::iterator i=global_symbol_dictionary.begin();i!=global_symbol_dictionary.end();++i)
             std::cout<<"  line "<<i->symbol_line<<": "<<i->symbol_name<<"|"<<i->symbol_number<<std::endl;
     }
     else
-        std::cout<<">>[Symbol] empty global symbol list."<<std::endl;
+        std::cout<<">> [Symbol] empty global symbol list."<<std::endl;
     if(!local_symbol_dictionary.empty())
     {
         std::cout<<">>[Symbol] local scope:"<<std::endl;
@@ -99,22 +108,19 @@ void nasal_symbol_table::print_symbol_table()
             std::cout<<"  line "<<i->symbol_line<<": "<<i->symbol_name<<"|"<<i->symbol_number<<std::endl;
     }
     else
-        std::cout<<">>[Symbol] empty local symbol list."<<std::endl;
+        std::cout<<">> [Symbol] empty local symbol list."<<std::endl;
     return;
 }
 
 void nasal_symbol_table::global_scope_add_symbol(symbol_table_unit tmp)
 {
-    int symbol_number_gen=0;
+    // this conditional expression is used to avoid wrong use of this function
+    // repeat symbol will get the same number
     for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
-    {
-        // this conditional expression is used to avoid wrong use of this function
-        // repeat symbol will get the same number
         if(i->symbol_name==tmp.symbol_name)
             return;
-        symbol_number_gen=i->symbol_number;
-    }
-    tmp.symbol_number=symbol_number_gen+1;
+    ++global_number;
+    tmp.symbol_number=global_number;
     global_scope.push_back(tmp);
     global_symbol_dictionary.push_back(tmp);
     return;
@@ -132,10 +138,13 @@ void nasal_symbol_table::local_list_del_scope()
     if(local_list.empty())
     {
         ++error;
-        std::cout<<">>[Symbol-error] fatal error: empty block_scope_list."<<std::endl;
+        std::cout<<">> [Symbol-error] fatal error: empty block_scope_list."<<std::endl;
     }
     else
         local_list.pop_back();
+    
+    if(local_list.empty())
+        local_number=0;
     return;
 }
 
@@ -143,61 +152,62 @@ void nasal_symbol_table::local_scope_add_symbol(symbol_table_unit tmp)
 {
     if(!local_list.empty())
     {
-        int symbol_number_gen=0;
-        // get last symbol number
-        for(std::list<std::list<symbol_table_unit> >::iterator i= local_list.begin();i!=local_list.end();++i)
-            if(!i->empty())
+        // if in the last scope there is a sym which symbol_name is the same as tmp.symbol_name
+        // then the symbol will get the same number
+        std::list<std::list<symbol_table_unit> >::iterator last_scope=local_list.end();--last_scope;
+        for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
                 for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
-                {
-                    // this conditional expression is used to avoid wrong use of this function
-                    // repeat symbol will get the same number
-                    ++i;
-                    if(i==local_list.end())
-                    {
-                        --i;
-                        if(j->symbol_name==tmp.symbol_name)
-                            return;
-                    }
-                    else
-                        --i;
-                    symbol_number_gen=j->symbol_number;
-                }
-        tmp.symbol_number=symbol_number_gen+1;
+                    if((i==last_scope) && (j->symbol_name==tmp.symbol_name))
+                        return;
+        ++local_number;
+        tmp.symbol_number=local_number;
         local_list.back().push_back(tmp);
         local_symbol_dictionary.push_back(tmp);
     }
     else
     {
         ++error;
-        std::cout<<">>[Symbol-error] fatal error: empty block_scope_list."<<std::endl;
+        std::cout<<">> [Symbol-error] fatal error: empty block_scope_list."<<std::endl;
     }
     return;
 }
 
 int nasal_symbol_table::search_symbol_id(symbol_table_unit tmp)
 {
-    // in both global and local scope
-    // symbol_number begins with 1
-    int ret_number=-1;
-    if(!local_list.empty())
-        for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
-            for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
-                if(j->symbol_name==tmp.symbol_name)
-                    ret_number=j->symbol_number;
-    if(ret_number==-1)
-        for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
-            if(i->symbol_name==tmp.symbol_name)
-                ret_number=i->symbol_number;
-    if(ret_number==-1)
-    {
-        ++error;
-        std::cout<<">>[Symbol-error] line "<<tmp.symbol_line<<": cannot find var named \'"<<tmp.symbol_name<<"\' ."<<std::endl;
-    }
-    return ret_number;
+    // local scope
+    for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
+        for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
+            if(j->symbol_name==tmp.symbol_name)
+                return j->symbol_number;
+    // global scope
+    for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
+        if(i->symbol_name==tmp.symbol_name)
+            return i->symbol_number;
+    // error
+    ++error;
+    std::cout<<">> [Symbol-error] line "<<tmp.symbol_line<<": cannot find var named \'"<<tmp.symbol_name<<"\' ."<<std::endl;
+    return -1;
+}
+
+bool nasal_symbol_table::search_scope(symbol_table_unit tmp)
+{
+	// this function must be used when search_symbol_id()!=-1
+	// because if seach_symbol_id()==-1 it means it haven't found this symbol
+	// true means global scope
+	// false means local scope
+    for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
+        for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
+            if(j->symbol_name==tmp.symbol_name)
+                return false;
+    for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
+        if(i->symbol_name==tmp.symbol_name)
+            return true;
+    return true;
 }
 
 int nasal_symbol_table::get_error()
 {
+    // god knows why i wrote this sh*t.
     return error;
 }
 
@@ -206,6 +216,7 @@ void nasal_symbol_table::symbol_table_main_generate(abstract_syntax_tree& root)
     this->set_scope_clear();
     for(std::list<abstract_syntax_tree>::iterator i=root.get_children().begin();i!=root.get_children().end();++i)
     {
+        // only definition will call this->global_scope_add_symbol(symbol_table_unit)
         if(i->get_node_type()==__definition)
         {
             symbol_table_unit tmp;
@@ -213,19 +224,21 @@ void nasal_symbol_table::symbol_table_main_generate(abstract_syntax_tree& root)
             tmp.symbol_name=i->get_children().front().get_var_name();
             this->global_scope_add_symbol(tmp);
             i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-            i->get_children().front().set_var_scope(true);
+            i->get_children().front().set_var_scope(this->search_scope(tmp));
             this->symbol_table_block_generate(i->get_children().back());
         }
+        // when in main_generate loop,local scope is totally empty
         else
             this->symbol_table_block_generate(*i);
     }
-    std::cout<<">>[Symbol] symbol table generating complete. "<<error<<" error(s)."<<std::endl;
+    std::cout<<">> [Symbol] symbol table generating complete. "<<error<<" error(s)."<<std::endl;
     return;
 }
 
 void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
 {
-    if(node.get_node_type()==__function)
+    int node_type=node.get_node_type();
+    if(node_type==__function)
     {
         this->local_list_add_scope();
         if(node.get_children().front().get_node_type()==__parameters)
@@ -238,7 +251,7 @@ void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
                     tmp.symbol_name=i->get_var_name();
                     this->local_scope_add_symbol(tmp);
                     i->set_symbol_number(this->search_symbol_id(tmp));
-                    i->set_var_scope(false);
+                    i->set_var_scope(this->search_scope(tmp));
                 }
                 else
                 {
@@ -247,14 +260,14 @@ void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
                     tmp.symbol_name=i->get_children().front().get_var_name();
                     this->local_scope_add_symbol(tmp);
                     i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-                    i->get_children().front().set_var_scope(false);
+                    i->get_children().front().set_var_scope(this->search_scope(tmp));
                     this->symbol_table_block_generate(i->get_children().back());
                 }
             }
         this->symbol_table_block_generate(node.get_children().back());
         this->local_list_del_scope();
     }
-    else if(node.get_node_type()==__conditional)
+    else if(node_type==__conditional)
     {
         for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
         {
@@ -265,7 +278,32 @@ void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
             this->local_list_del_scope();
         }
     }
-    else if(node.get_node_type()==__normal_statement_block)
+    else if(node_type==__while)
+    {
+        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
+            this->symbol_table_block_generate(*i);
+    }
+    else if(node_type==__for || node_type==__foreach || node_type==__forindex)
+    {
+        this->local_list_add_scope();
+        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
+        {
+            if(i->get_node_type()==__definition)
+            {
+                symbol_table_unit tmp;
+                tmp.symbol_line=i->get_children().front().get_node_line();
+                tmp.symbol_name=i->get_children().front().get_var_name();
+                this->local_scope_add_symbol(tmp);
+                i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
+                i->get_children().front().set_var_scope(this->search_scope(tmp));
+                this->symbol_table_block_generate(i->get_children().back());
+            }
+            else
+                this->symbol_table_block_generate(*i);
+        }
+        this->local_list_del_scope();
+    }
+    else if(node_type==__normal_statement_block)
     {
         for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
         {
@@ -276,22 +314,29 @@ void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
                 tmp.symbol_name=i->get_children().front().get_var_name();
                 this->local_scope_add_symbol(tmp);
                 i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-                i->get_children().front().set_var_scope(false);
+                i->get_children().front().set_var_scope(this->search_scope(tmp));
                 this->symbol_table_block_generate(i->get_children().back());
             }
             else
                 this->symbol_table_block_generate(*i);
         }
     }
-    else if(node.get_node_type()==__id)
+    else if(node_type==__id)
     {
         symbol_table_unit tmp;
         tmp.symbol_line=node.get_node_line();
         tmp.symbol_name=node.get_var_name();
         int id_symbol_number=this->search_symbol_id(tmp);
         node.set_symbol_number(id_symbol_number);
+        // if this id does not exist in scopes
+        // then search_scope will not be called
+        if(id_symbol_number>0)
+        	node.set_var_scope(this->search_scope(tmp));
+        if(!node.get_children().empty())
+            for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
+                this->symbol_table_block_generate(*i);
     }
-    else if(node.get_node_type()==__hash)
+    else if(node_type==__hash)
     {
         this->local_list_add_scope();
         symbol_table_unit me;
@@ -310,7 +355,7 @@ void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
 	                tmp.symbol_name=i->get_children().front().get_var_string();
 	            this->local_scope_add_symbol(tmp);
 	            i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-	            i->get_children().front().set_var_scope(false);
+	            i->get_children().front().set_var_scope(this->search_scope(tmp));
 	            this->symbol_table_block_generate(i->get_children().back());
 			}
 			else