diff --git a/nasal.h b/nasal.h
index 3d16a59..e5dca51 100644
--- a/nasal.h
+++ b/nasal.h
@@ -1,23 +1,17 @@
 #ifndef __NASAL_H__
 #define __NASAL_H__
 
-#include "nasal_hash.cpp"
+#include <iostream>
+#include <cstring>
+#include "nasal_list.h"
+#include "nasal_func.h"
+#include "nasal_hash.h"
+
 #include "nasal_list.cpp"
-#include "nasal_print.h"
+#include "nasal_hash.cpp"
 
-// int
-// char
-// long long int
-// double 
-// float
-// string
-// const char *
-// NasalHash
-// NasalList
+#include "nasal_var_stack.h"
+#include "nasal_func_stack.h"
+#include "nasal_lexer.h"
 
-/*
-NasalList->delete NasalList & NasalHash
-
-NasalHash->delete NasalList & NasalHash
-*/
 #endif
diff --git a/nasal_func.h b/nasal_func.h
new file mode 100644
index 0000000..f4d00a0
--- /dev/null
+++ b/nasal_func.h
@@ -0,0 +1,156 @@
+#ifndef __NASAL_FUNC_H__
+#define __NASAL_FUNC_H__
+
+#include <iostream>
+#include <cstring>
+
+namespace nasal
+{
+
+struct func_unit
+{
+	std::string type;
+	std::string content;
+	int line;
+	func_unit *next;
+};
+
+class func
+{
+	private:
+		func_unit *head;
+	public:
+		func()
+		{
+			head=new func_unit;
+			head->type="Begin";
+			head->content="__process_begin";
+			head->line=0;
+			head->next=NULL;
+		}
+		~func()
+		{
+			func_unit *temp=head;
+			func_unit *this_node=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+		}
+		void delete_all()
+		{
+			if(!head->next)
+				return;
+			func_unit *temp=head;
+			func_unit *this_node=NULL;
+			temp=temp->next;
+			head->next=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+			return;
+		}
+		void append(const char *_type,std::string &_content,const int _line)
+		{
+			func_unit *temp=head;
+			while(temp->next)
+				temp=temp->next;
+			temp->next=new func_unit;
+			temp=temp->next;
+			temp->next=NULL;
+			temp->type=_type;
+			temp->line=_line;
+			temp->content=_content;
+			return;
+		}
+		void print()
+		{
+			func_unit *temp=head;
+			std::cout<<"line "<<temp->line<<": "<<"( ProcessBegin | "<<temp->content<<" )"<<std::endl;
+			if(!head->next)
+				return;
+			while(temp->next)
+			{
+				temp=temp->next;
+				std::cout<<"line "<<temp->line<<": ";
+				if(temp->type=="Operator")
+					std::cout<<"( Operator     | ";
+				else if(temp->type=="Identifier")
+					std::cout<<"( Identifier   | ";
+				else if(temp->type=="Number")
+					std::cout<<"( Number       | ";
+				else if(temp->type=="ReserveWord")
+					std::cout<<"( ReserveWord  | ";
+				else if(temp->type=="String")
+					std::cout<<"( String       | ";
+				std::cout<<temp->content<<" )"<<std::endl;
+			}
+			return;
+		}
+		func& operator=(const func &p)
+		{
+			delete_all();
+			func_unit *temp=head;
+			func_unit *ptemp=p.head;
+			while(ptemp->next)
+			{
+				ptemp=ptemp->next;
+				temp=new func_unit;
+				temp->type=ptemp->type;
+				temp->content=ptemp->content;
+				temp->line=ptemp->line;
+				temp->next=NULL;
+			}
+			temp=new func_unit;
+			temp->type=ptemp->type;
+			temp->content=ptemp->content;
+			temp->line=ptemp->line;
+			temp->next=NULL;
+			return *this;
+		}
+		void run()
+		{
+			func_unit *temp=head;
+			if(!head->next)
+			{
+				std::cout<<"Running complete."<<std::endl;
+				return;
+			}
+			while(temp->next)
+			{
+				temp=temp->next;
+				if(temp->type=="Operator")
+				{
+					;
+				}
+				else if(temp->type=="Identifier")
+				{
+					;
+				}
+				else if(temp->type=="Number")
+				{
+					;
+				}
+				else if(temp->type=="ReserveWord")
+				{
+					;
+				}
+				else if(temp->type=="String")
+				{
+					;
+				}
+			}
+			return;
+		}
+};
+
+}
+
+#endif
diff --git a/nasal_func_stack.h b/nasal_func_stack.h
new file mode 100644
index 0000000..ea75dde
--- /dev/null
+++ b/nasal_func_stack.h
@@ -0,0 +1,103 @@
+#ifndef __NASAL_FUNC_STACK_H__
+#define __NASAL_FUNC_STACK_H__
+
+#include "nasal_func.h"
+
+
+namespace nasal
+{
+
+struct func_stack_unit
+{
+	std::string func_name;
+	func func_statement;
+	func_stack_unit *next;
+};
+
+class func_stack
+{
+	private:
+		func_stack_unit *head;
+	public:
+		func_stack()
+		{
+			head=new func_stack_unit;
+			head->func_name="null";
+			head->next=NULL;
+		}
+		~func_stack()
+		{
+			func_stack_unit *temp=head;
+			func_stack_unit *this_node=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+		}
+		void append_function(std::string &function_name,func &temp_func)
+		{
+			func_stack_unit *temp=head;
+			while(temp->next)
+			{
+				temp=temp->next;
+				if(temp->func_name==function_name)
+				{
+					std::cout<<"[Error] Redeclaration of function \""<<function_name<<"\""<<std::endl;
+					return;
+				}
+			}
+			temp->next=new func_stack_unit;
+			temp=temp->next;
+			temp->next=NULL;
+			temp->func_statement=temp_func;
+			return;
+		}
+		void run_function(std::string &function_name)
+		{
+			func_stack_unit *temp=head;
+			while(temp->next)
+			{
+				temp=temp->next;
+				if(temp->func_name==function_name)
+				{
+					temp->func_statement.run();
+					return;
+				}
+			}
+			std::cout<<"[Error] Could not find this function."<<std::endl;
+			return;
+		}
+		void print_function()
+		{
+			func_stack_unit *temp=head;
+			while(temp->next)
+			{
+				temp=temp->next;
+				std::cout<<"function: "<<temp->func_name<<std::endl;
+			}
+			std::cout<<"function: "<<temp->func_name<<std::endl;
+			return;
+		}
+		void pop_function()
+		{
+			func_stack_unit *temp=head;
+			func_stack_unit *end_temp;
+			if(!head->next)
+				return;
+			while(temp->next)
+			{
+				end_temp=temp;
+				temp=temp->next;
+			}
+			end_temp->next=NULL;
+			delete temp;
+		}
+};
+
+}
+
+
+#endif
diff --git a/nasal_functional.h b/nasal_functional.h
new file mode 100644
index 0000000..ad1816b
--- /dev/null
+++ b/nasal_functional.h
@@ -0,0 +1,141 @@
+#ifndef __NASAL_FUNCTIONAL_H__
+#define __NASAL_FUNCTIONAL_H__
+
+#include <iostream>
+#include <cstring>
+
+namespace nasal
+{
+
+#define FUNC_OPERATOR    1
+#define FUNC_IDENTIFIER  2
+#define FUNC_NUMBER      3
+#define FUNC_RESERVEWORD 4
+#define FUNC_STRING      5
+
+struct token_unit
+{
+	std::string type;
+	std::string content;
+	int line;
+	token_unit *next;
+};
+
+class token_list
+{
+	private:
+		token_unit *head;
+	public:
+		token_list()
+		{
+			head=new token_unit;
+			head->type="Begin";
+			head->content="__process_begin";
+			head->line=0;
+			head->next=NULL;
+		}
+		~token_list()
+		{
+			token_unit *temp=head;
+			token_unit *this_node=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+		}
+		void delete_all()
+		{
+			if(!head->next)
+				return;
+			token_unit *temp=head;
+			token_unit *this_node=NULL;
+			temp=temp->next;
+			head->next=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+			return;
+		}
+		void append(const char *_type,std::string &_content,const int _line)
+		{
+			token_unit *temp=head;
+			while(temp->next)
+				temp=temp->next;
+			temp->next=new token_unit;
+			temp=temp->next;
+			temp->next=NULL;
+			temp->type=_type;
+			temp->line=_line;
+			temp->content=_content;
+			return;
+		}
+		void print()
+		{
+			token_unit *temp=head;
+			std::cout<<"line "<<temp->line<<": "<<"( ProcessBegin | "<<temp->content<<" )"<<std::endl;
+			if(!head->next)
+				return;
+			while(temp->next)
+			{
+				temp=temp->next;
+				std::cout<<"line "<<temp->line<<": ";
+				if(temp->type=="Operator")
+					std::cout<<"( Operator     | ";
+				else if(temp->type=="Identifier")
+					std::cout<<"( Identifier   | ";
+				else if(temp->type=="Number")
+					std::cout<<"( Number       | ";
+				else if(temp->type=="ReserveWord")
+					std::cout<<"( ReserveWord  | ";
+				else if(temp->type=="String")
+					std::cout<<"( String       | ";
+				std::cout<<temp->content<<" )"<<std::endl;
+			}
+			return;
+		}
+		void run()
+		{
+			token_unit *temp=head;
+			if(!head->next)
+			{
+				std::cout<<"Running complete."<<std::endl;
+				return;
+			}
+			while(temp->next)
+			{
+				temp=temp->next;
+				if(temp->type=="Operator")
+				{
+					;
+				}
+				else if(temp->type=="Identifier")
+				{
+					;
+				}
+				else if(temp->type=="Number")
+				{
+					;
+				}
+				else if(temp->type=="ReserveWord")
+				{
+					;
+				}
+				else if(temp->type=="String")
+				{
+					;
+				}
+			}
+		}
+};
+
+}
+
+
+#endif
diff --git a/nasal_hash.cpp b/nasal_hash.cpp
index 83fb8dc..e4f0dcc 100644
--- a/nasal_hash.cpp
+++ b/nasal_hash.cpp
@@ -445,35 +445,22 @@ NasalHash& NasalHash::operator=(const NasalHash &Source)
 	return *this;
 }
 
-void NasalHash::SearchElement(std::string &ElementName)
+HashUnit NasalHash::SearchElement(std::string &ElementName)
 {
 	HashUnit *temp=head;
 	while(temp->next)
 	{
 		temp=temp->next;
 		if(temp->VarName==ElementName)
-		{
-			if(temp->Type=="int")
-				std::cout<<*((int *)temp->data);
-			else if(temp->Type=="float")
-				std::cout<<*((float *)temp->data);
-			else if(temp->Type=="double")
-				std::cout<<*((double *)temp->data);
-			else if(temp->Type=="char")
-				std::cout<<*((char *)temp->data);
-			else if(temp->Type=="long long int")
-				std::cout<<*((long long int *)temp->data);
-			else if(temp->Type=="string")
-				std::cout<<*((std::string *)temp->data);
-			else if(temp->Type=="array")
-				((NasalList *)temp->data)->PrintList();
-			else if(temp->Type=="hash")
-				((NasalHash *)temp->data)->PrintHash();
-			return;
-		}
+			return *temp;
 	}
 	std::cout<<"[Error] Could not find \""<<ElementName<<"\""<<std::endl;
-	return;
+	HashUnit nil_hash;
+	nil_hash.data=NULL;
+	nil_hash.next=NULL;
+	nil_hash.Type="null";
+	nil_hash.VarName="null";
+	return nil_hash;
 }
 
 }
diff --git a/nasal_hash.h b/nasal_hash.h
index a2e74d1..d76270d 100644
--- a/nasal_hash.h
+++ b/nasal_hash.h
@@ -33,7 +33,7 @@ class NasalHash
 		NasalList Keys();
 		void Delete(const char *);
 		NasalHash& operator=(const NasalHash&);
-		void SearchElement(std::string &);
+		HashUnit SearchElement(std::string &);
 };
 
 }
diff --git a/nasal_lexer.h b/nasal_lexer.h
new file mode 100644
index 0000000..fa2a29d
--- /dev/null
+++ b/nasal_lexer.h
@@ -0,0 +1,277 @@
+#ifndef __NASAL_LEXER_H__
+#define __NASAL_LEXER_H__
+
+
+#include <iostream>
+#include <fstream>
+#include <cstring>
+#include "nasal_functional.h"
+
+namespace nasal
+{
+
+#define IDENTIFIER  -1 //自定义标识符 
+#define OPERATOR    -2 //界符 or 运算符 
+#define NUMBER      -3 //数字 
+#define RESERVEWORD -4 //关键字 
+#define STRING      -5 //字符串类型 
+#define FAIL        -6 //失败 
+#define SCANEND     -7 //扫描完成 
+#define ERRORFOUND  -8 //异常错误 
+
+std::string ReserveWord[26]=
+{
+	"for","foreach","forindex","while",
+	"var","func","break","continue","return",
+	"if","else","elsif","nil","and","or",
+	"print","cmp","append","setsize","subvec","pop",
+	"sort","contains","delete","keys","typeof"
+};
+
+std::string OperatorOrDelimiter[40]=
+{
+	"+","-","*","/","=","+=","-=","*=","/=",
+	"\n","\t","\r","\\","\'","\"",".",
+	"<","<=",">",">=","==","!=","~=","!","~",
+	",",";","(",")","[","]","{","}","#","?",":",
+	"&","|","%","^"
+};
+
+std::string IdentifierTable[1000]={""};
+char ResourcePrograme[16777216];
+
+int isReserveWord(std::string &p)
+{
+	for(int i=0;i<26;++i)
+		if(ReserveWord[i]==p)
+			return i+1;
+	return FAIL;
+}
+
+int isOperatorOrDelimiter(std::string &p)
+{
+	for(int i=0;i<40;++i)
+		if(OperatorOrDelimiter[i]==p)
+			return i+1;
+	return FAIL;
+}
+
+bool isLetter(char t)
+{
+	return (('a'<=t) && (t<='z') || ('A'<=t) && (t<='Z'));
+}
+
+bool isNumber(char t)
+{
+	return (('0'<=t) && (t<='9'));
+}
+
+void InputFile(std::string &FileName)
+{
+	std::ifstream fin(FileName);
+	if(fin.fail())
+	{
+		std::cout<<"[Error] Failed to load file: "<<FileName<<std::endl;
+		ResourcePrograme[0]='@';
+		fin.close();
+		return;
+	}
+	int i=0;
+	bool FindNote=false;
+	while(!fin.eof())
+	{
+		ResourcePrograme[i]=fin.get();
+		if(ResourcePrograme[i]=='\n')
+			FindNote=false;
+		if(ResourcePrograme[i]!='#' && !FindNote)
+			++i;
+		else if(ResourcePrograme[i]=='#')
+		{
+			FindNote=true;
+		}
+		if(fin.eof())
+			break;
+	}
+	ResourcePrograme[i]='@';
+//	print source file
+//	++i;
+//	for(int j=0;j<i;++j)
+//		std::cout<<ResourcePrograme[j];
+//	std::cout<<std::endl;
+	fin.close();
+	return;
+}
+
+void Scanner(int &Syn,const char Source[],std::string &token,int &ptr,int &line)
+{
+	char temp;
+	temp=Source[ptr];
+	while(temp==' ' || temp=='\n' || temp=='\t' || temp=='\r' || temp<0 || temp>127)
+	{
+		++ptr;
+		if(temp=='\n')
+			++line;
+		temp=Source[ptr];
+	}
+	
+	token="";
+	if(isLetter(temp) || temp=='_')
+	{
+		token+=temp;
+		++ptr;
+		temp=Source[ptr];
+		while(isLetter(temp) || isNumber(temp) || temp=='_')
+		{
+			token+=temp;
+			++ptr;
+			temp=Source[ptr];
+		}
+		Syn=isReserveWord(token);
+		if(Syn==FAIL)
+			Syn=IDENTIFIER;
+		else
+			Syn=RESERVEWORD;
+	}
+	else if(isNumber(temp))
+	{
+		int PointCnt=0;
+		while(isNumber(temp))
+		{
+			token+=temp;
+			++ptr;
+			temp=Source[ptr];
+			if(temp=='.' && !PointCnt)
+			{
+				++PointCnt;
+				token+=temp;
+				++ptr;
+				temp=Source[ptr];
+			}
+		}
+		Syn=NUMBER;
+	}
+	else if(temp=='(' || temp==')' || temp=='[' || temp==']' || temp=='{' ||
+			temp=='}' || temp==',' || temp==';' || temp=='|' || temp==':' ||
+			temp=='?' || temp=='.' || temp=='`' || temp=='\'' || temp=='&'||
+			temp=='%' || temp=='$' || temp=='^')
+	{
+		token+=temp;
+		++ptr;
+		Syn=OPERATOR;
+	}
+	else if(temp=='=' || temp=='+' || temp=='-' || temp=='*' || temp=='!' || temp=='/' || temp=='<' || temp=='>' || temp=='~')
+	{
+		Syn=OPERATOR;
+		token+=temp;
+		++ptr;
+		temp=Source[ptr];
+		if(temp=='=')
+		{
+			token+=temp;
+			++ptr;
+		}
+	}
+	else if(temp=='\\')
+	{
+		Syn=OPERATOR;
+		token+=temp;
+		++ptr;
+		temp=Source[ptr];
+		if(temp=='=' || temp=='n' || temp=='t' || temp=='r' || temp=='\\' || temp=='\'' || temp=='\"')
+		{
+			token+=temp;
+			++ptr;
+		}
+	}
+	else if(temp=='\"')
+	{
+		Syn=STRING;
+		token+=temp;
+		++ptr;
+		temp=Source[ptr];
+		while(temp!='\"')
+		{
+			if(temp=='\\')
+			{
+				token+=temp;
+				
+				++ptr;
+				temp=Source[ptr];
+				token+=temp;
+				
+				++ptr;
+				temp=Source[ptr];
+			}
+			else
+			{
+				token+=temp;
+				++ptr;
+				temp=Source[ptr];
+			}
+			if(temp=='@' || temp=='\n')
+				break;
+		}
+		//add the last char \"
+		if(temp=='\"')
+		{
+			token+=temp;
+			++ptr;
+		}
+		else
+			token+=" __missing_end_of_string";
+	}
+	else if(temp=='@')
+	{
+		Syn=SCANEND;
+		return;
+	}
+	else
+	{
+		Syn=FAIL;
+		std::cout<<"[Error] Unexpected error occurred: "<<temp<<std::endl;
+		system("pause");
+		++ptr;
+		return;
+	}
+	if(token=="")
+	{
+		Syn=ERRORFOUND;
+		std::cout<<"[Error] Cannot identify "<<std::endl;
+	}
+	return;
+}
+
+token_list lexer;
+
+void RunProcess(std::string &FileNameOrCommand)
+{
+	int Syn=0;//token type
+	int Ptr=0;//pointer to one char in ResourcePrograme
+	int line=1;
+	std::string token;
+	
+	InputFile(FileNameOrCommand);
+	while(Syn!=SCANEND && Syn!=ERRORFOUND)
+	{
+		Scanner(Syn,ResourcePrograme,token,Ptr,line);
+		if(Syn==OPERATOR)
+			lexer.append("Operator",token,line);
+		else if(Syn==IDENTIFIER)
+			lexer.append("Identifier",token,line);
+		else if(Syn==NUMBER)
+			lexer.append("Number",token,line);
+		else if(Syn==RESERVEWORD)
+			lexer.append("ReserveWord",token,line);
+		else if(Syn==STRING)
+			lexer.append("String",token,line);
+	}
+	lexer.print();
+	std::cout<<">> Complete scanning \""<<FileNameOrCommand<<"\"."<<std::endl;
+	return;
+}
+
+
+
+
+}
+#endif
diff --git a/nasal_list.cpp b/nasal_list.cpp
index 42a8903..a9ace9b 100644
--- a/nasal_list.cpp
+++ b/nasal_list.cpp
@@ -612,6 +612,14 @@ NasalList NasalList::SubVec(const int start,const int length=nil)
 var NasalList::Pop()
 {
 	ListUnit *temp=head;
+	if(!head->next)
+	{
+		var temp_var;
+		temp_var.data=NULL;
+		temp_var.Type="null";
+		temp_var.isGlobal=false;
+		return temp_var;
+	}
 	ListUnit *NewLastUnit;
 	while(temp->next)
 	{
@@ -819,7 +827,7 @@ NasalList NasalList::Sort(const int SortType,const int _cmp)
 	return TempList;
 }
 
-void NasalList::SearchElement(const int n)
+ListUnit NasalList::SearchElement(const int n)
 {
 	if(n<0)
 	{
@@ -832,12 +840,14 @@ void NasalList::SearchElement(const int n)
 		temp=temp->next;
 		cnt++;
 		if(cnt==n)
-		{
-			return;
-		}
+			return *temp;
 	}
 	std::cout<<"[Error] Out of range: real end: "<<cnt<<", less than "<<n<<"."<<std::endl;
-	return;
+	ListUnit nil_list;
+	nil_list.data=NULL;
+	nil_list.next=NULL;
+	nil_list.Type="null";
+	return nil_list;
 }
 
 var::var(var &p)
@@ -930,6 +940,7 @@ var& var::operator=(const var &p)
 			delete (NasalHash *)data;
 	}
 	Type=p.Type;
+	isGlobal=p.isGlobal;
 	if(Type=="int")
 	{
 		data=new int;
diff --git a/nasal_list.h b/nasal_list.h
index a7ba586..e73d7ff 100644
--- a/nasal_list.h
+++ b/nasal_list.h
@@ -36,7 +36,7 @@ class NasalList
 		NasalList SubVec(const int,const int);
 		var Pop();
 		NasalList Sort(const int,const int);
-		void SearchElement(const int);
+		ListUnit SearchElement(const int);
 };
 
 class var
@@ -44,6 +44,7 @@ class var
 	public:
 		std::string Type;
 		void *data;
+		bool isGlobal;
 		var()
 		{
 			data=NULL;
diff --git a/nasal_print.h b/nasal_print.h
index 5086c4a..8c6a07a 100644
--- a/nasal_print.h
+++ b/nasal_print.h
@@ -9,25 +9,26 @@
 namespace nasal
 {
 	
-void PrintVar(int Var)
+void PrintVar(var &Var)
 {
-	std::cout<<Var;
-}
-void PrintVar(float Var)
-{
-	std::cout<<Var;
-}
-void PrintVar(double Var)
-{
-	std::cout<<Var;
-}
-void PrintVar(char Var)
-{
-	std::cout<<Var;
-}
-void PrintVar(long long int Var)
-{
-	std::cout<<Var;
+	if(Var.Type=="int")
+		std::cout<<*((int *)Var.data);
+	else if(var.Type=="long long int")
+		std::cout<<*((long long int Var.data));
+	else if(Var.Type=="float")
+		std::cout<<*((float *)Var.data);
+	else if(Var.Type=="double")
+		std::cout<<*((double *)Var.data);
+	else if(Var.Type=="char")
+		std::cout<<*((char *)Var.data);
+	else if(Var.Type=="string")
+		std::cout<<*((std::string *)Var.data);
+	else if(Var.Type=="array")
+		((NasalList *)Var.data)->PrintList();
+	else if(Var.Type=="hash")
+		((NasalHash *)Var.data)->PrintHash();
+	else
+		std::cout<<"null";
 }
 void PrintVar(NasalHash &Var)
 {
@@ -88,7 +89,7 @@ void PrintString(std::string &PrintInfo)
 	}
 	return;
 }
-
+/*
 void PrintString(const char *PrintInfo)
 {
 	for(int i=0;i<strlen(PrintInfo);++i)
@@ -138,6 +139,7 @@ void PrintString(const char *PrintInfo)
 	}
 	return;
 }
+*/
 
 }
 
diff --git a/nasal_var_stack.h b/nasal_var_stack.h
new file mode 100644
index 0000000..793e32a
--- /dev/null
+++ b/nasal_var_stack.h
@@ -0,0 +1,100 @@
+#ifndef __NASAL_VAR_STACK_H__
+#define __NASAL_VAR_STACK_H__
+
+#include "nasal_list.h"
+#include "nasal_print.h"
+
+
+namespace nasal
+{
+
+struct var_stack_unit
+{
+	std::string var_name;
+	var var_detail;
+	var_stack_unit *next;
+};
+
+class var_stack
+{
+	private:
+		var_stack_unit *head;
+	public:
+		var_stack()
+		{
+			head=new var_stack_unit;
+			head->var_name="null";
+			head->next=NULL;
+		}
+		~var_stack()
+		{
+			var_stack_unit *temp=head;
+			var_stack_unit *this_node=NULL;
+			while(temp->next)
+			{
+				this_node=temp;
+				temp=temp->next;
+				delete this_node;
+			}
+			delete temp;
+		}
+		void append_var(std::string &varia_name,var &temp_var)
+		{
+			var_stack_unit *temp=head;
+			while(temp->next)
+				temp=temp->next;
+			temp->next=new var_stack_unit;
+			temp=temp->next;
+			temp->var_name=varia_name;
+			temp->var_detail=temp_var;
+			temp->next=NULL;
+		}
+		void print_var()
+		{
+			var_stack_unit *temp=head;
+			while(temp->next)
+			{
+				temp=temp->next;
+				std::cout<<"["<<temp->var_detail.Type<<"]: "<<temp->var_name;
+				PrintVar(temp->var_detail);
+				std::cout<<endl;
+			}
+			std::cout<<"["<<temp->var_detail.Type<<"]: "<<temp->var_name;
+			PrintVar(temp->var_detail);
+			std::cout<<endl;
+			return;
+		}
+		var &SearchVar(std::string varia_name)
+		{
+			var temp_var;
+			temp_var.data=NULL;
+			temp_var.Type="null";
+			temp_var.isGlobal=false;
+			var_stack_unit *temp=head;
+			while(temp->next)
+			{
+				temp=temp->next;
+				if(temp->var_name==varia_name)
+					temp_var=temp->var_detail;
+			}
+			return temp_var;
+		}
+		void pop_var()
+		{
+			var_stack_unit *temp=head;
+			var_stack_unit *end_temp;
+			if(!head->next)
+				return;
+			while(temp->next)
+			{
+				end_temp=temp;
+				temp=temp->next;
+			}
+			end_temp->next=NULL;
+			delete temp;
+		}
+};
+
+}
+
+#endif