diff --git a/README.md b/README.md
index 3fabe9b..16f2c3f 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,28 @@ Better choose the latest update of the interpreter.
 
 MUST USE -O2 ! pragma gcc optimize(2) seems useless when using g++
 
-> g++ -std=c++11 -O2 main.cpp -o main.exe
+> g++ -std=c++11 -O2 main.cpp -o nasal.exe
+
+Or use this in linux/macOS/Unix
+
+> g++ -std=c++11 -O2 main.cpp -o nasal
+
+## How to Use?
+
+Input this command to use interactive interpreter mode:
+
+> ./nasal
+
+Input this command to run scripts directly:
+
+> ./nasal filename
+
+Use these commands to get some information of interpreter:
+
+> ./nasal -v
+> ./nasal -version
+> ./nasal -h
+> ./nasal -help
 
 ## Parser
 
@@ -471,7 +492,7 @@ After that, write the built-in function's name(in nasal) and the function's poin
 ```C++
 struct FUNC_TABLE
 {
-    std::string name;
+    const char* name;
     nasal_val* (*func)(std::vector<nasal_val*>&,nasal_gc&);
 } builtin_func[]=
 {
diff --git a/lib.nas b/lib.nas
index c1b031d..8de85cc 100644
--- a/lib.nas
+++ b/lib.nas
@@ -1,28 +1,23 @@
 var import=func(filename)
 {
-    __builtin_import(filename);
-    return nil;
+    return __builtin_import(filename);
 }
-var print=func(elements...)
+var print=func(elems...)
 {
-    __builtin_std_cout(elements);
-    return nil;
+    return __builtin_std_cout(elems);
 };
-var println=func(elements...)
+var println=func(elems...)
 {
-    __builtin_std_cout(elements);
-    print('\n');
-    return nil;
+    __builtin_std_cout(elems);
+    return print('\n');
 }
-var append=func(vector,elements...)
+var append=func(vec,elems...)
 {
-    __builtin_push_back(vector,elements);
-    return nil;
+    return __builtin_push_back(vec,elems);
 }
-var setsize=func(vector,size)
+var setsize=func(vec,size)
 {
-    __builtin_set_size(vector,size);
-    return nil;
+    return __builtin_set_size(vec,size);
 }
 var system=func(str)
 {
@@ -34,36 +29,35 @@ var input=func()
 }
 var sleep=func(duration)
 {
-    __builtin_sleep(duration);
-    return;
+    return __builtin_sleep(duration);
 }
-var split=func(delimeter,string)
+var split=func(deli,str)
 {
-    return __builtin_split(delimeter,string);
+    return __builtin_split(deli,str);
 }
 var rand=func(seed=nil)
 {
     return __builtin_rand(seed);
 }
-var id=func(thing)
+var id=func(object)
 {
-    return __builtin_get_id(thing);
+    return __builtin_get_id(object);
 }
-var int=func(value)
+var int=func(val)
 {
-    return __builtin_int(value);
+    return __builtin_int(val);
 }
-var num=func(value)
+var num=func(val)
 {
-    return __builtin_num(value);
+    return __builtin_num(val);
 }
-var pop=func(vector)
+var pop=func(vec)
 {
-    return __builtin_pop_back(vector);
+    return __builtin_pop_back(vec);
 }
-var str=func(number)
+var str=func(num)
 {
-    return __builtin_str(number);
+    return __builtin_str(num);
 }
 var size=func(object)
 {
@@ -75,8 +69,7 @@ var contains=func(hash,key)
 }
 var delete=func(hash,key)
 {
-    __builtin_delete(hash,key);
-    return;
+    return __builtin_delete(hash,key);
 }
 var keys=func(hash)
 {
@@ -88,49 +81,41 @@ var time=func(begin_time)
 }
 var die=func(str)
 {
-    __builtin_die(str);
-    return nil;
+    return __builtin_die(str);
 }
 var typeof=func(object)
 {
     return __builtin_type(object);
 }
-var substr=func(str,begin,length)
+var substr=func(str,begin,len)
 {
-    return __builtin_substr(str,begin,length);
+    return __builtin_substr(str,begin,len);
 }
 var streq=func(a,b)
 {
     return __builtin_streq(a,b);
 }
-var left=func(string,length)
+var left=func(str,len)
 {
-    return __builtin_left(string,length);
+    return __builtin_left(str,len);
 }
-var right=func(string,length)
+var right=func(str,len)
 {
-    return __builtin_right(string,length);
+    return __builtin_right(str,len);
 }
 var cmp=func(a,b)
 {
     return __builtin_cmp(a,b);
 }
-var chr=func(code) #//Unlike in FG, this chr does not support Extended ASCII
+var chr=func(code)
 {
     return __builtin_chr(code);
 }
 
 var io=
 {
-    fin:func(filename)
-    {
-        return __builtin_fin(filename);
-    },
-    fout:func(filename,str)
-    {
-        __builtin_fout(filename,str);
-        return;
-    }
+    fin: func(filename){return __builtin_fin(filename);},
+    fout:func(filename,str){return __builtin_fout(filename,str);}
 };
 
 var bits=
diff --git a/main.cpp b/main.cpp
index 67a85d6..3d337d5 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,10 +2,10 @@
 
 nasal_vm vm;
 
-void help()
+void help_interact()
 {
 	std::cout
-	<<">> [\"file\"] input file name.            \n"
+	<<">> [     ] input a file name to execute.  \n"
 	<<">> [help ] show help.                     \n"
 	<<">> [clear] clear the screen.              \n"
 	<<">> [lex  ] view tokens.                   \n"
@@ -16,7 +16,25 @@ void help()
 	<<">> [exit ] quit nasal interpreter.        \n";
 	return;
 }
-
+void help_cmd()
+{
+	std::cout
+	<<"nasal -h -help    | get help.\n"
+	<<"nasal -v -version | get version of nasal interpreter.\n"
+	<<"nasal filename    | execute script file.\n";
+	return;
+}
+void info()
+{
+	std::cout
+	<<">> Nasal interpreter ver 6.5 efficient gc test .\n"
+	<<">> Thanks to https://github.com/andyross/nasal\n"
+	<<">> Code: https://github.com/ValKmjolnir/Nasal-Interpreter\n"
+	<<">> Code: https://gitee.com/valkmjolnir/Nasal-Interpreter\n"
+	<<">> Info: http://wiki.flightgear.org/Nasal_scripting_language\n"
+	<<">> Input \"help\" to get help .\n";
+	return;
+}
 void logo()
 {
     std::cout
@@ -27,13 +45,11 @@ void logo()
 	<<"  \\_\\ \\/ \\__,_|___/\\__,_|_|\n";
     return;
 }
-
 void die(const char* stage,std::string& filename)
 {
 	std::cout<<">> ["<<stage<<"] in <\""<<filename<<"\">: error(s) occurred,stop.\n";
 	return;
 }
-
 void execute(std::string& file,std::string& command)
 {
 	nasal_lexer   lexer;
@@ -92,31 +108,21 @@ void execute(std::string& file,std::string& command)
 	vm.clear();
 	return;
 }
-
-int main()
+void interact()
 {
-	std::string command;
-	std::string file="null";
 #ifdef _WIN32
 	// use chcp 65001 to use unicode io
 	system("chcp 65001");
-	system("cls");
-#else
-	int rs=system("clear");// avoid annoying warning of high version gcc/g++
 #endif
+	std::string command,file="null";
 	logo();
-	std::cout<<">> Nasal interpreter ver 6.5 efficient gc test .\n";
-	std::cout<<">> Thanks to https://github.com/andyross/nasal\n";
-	std::cout<<">> Code: https://github.com/ValKmjolnir/Nasal-Interpreter\n";
-	std::cout<<">> Code: https://gitee.com/valkmjolnir/Nasal-Interpreter\n";
-	std::cout<<">> Info: http://wiki.flightgear.org/Nasal_scripting_language\n";
-	std::cout<<">> Input \"help\" to get help .\n";
+	info();
     while(1)
 	{
 		std::cout<<">> ";
 		std::cin>>command;
 		if(command=="help")
-			help();
+			help_interact();
 		else if(command=="clear")
 		{
 #ifdef _WIN32
@@ -128,11 +134,33 @@ int main()
 		else if(command=="logo")
 			logo();
 		else if(command=="exit")
-			break;
+			return;
 		else if(command=="lex" || command=="ast" || command=="code" || command=="exec")
 			execute(file,command);
 		else
 			file=command;
 	}
+}
+int main(int argc,const char* argv[])
+{
+	std::string command,file="null";
+	if(argc==1)
+		interact();
+	else if(argc==2 && (!strcmp(argv[1],"-v") || !strcmp(argv[1],"-version")))
+	{
+		logo();
+		std::cout<<"Nasal interpreter ver 6.5 efficient gc test\n";
+	}
+	else if(argc==2 && (!strcmp(argv[1],"-h") || !strcmp(argv[1],"-help")))
+		help_cmd();
+	else if(argc==2)
+	{
+		file=argv[1];
+		command="exec";
+		execute(file,command);
+		return 0;
+	}
+	else
+		help_cmd();
     return 0;
 }
\ No newline at end of file
diff --git a/nasal.h b/nasal.h
index 3521492..f31c8b1 100644
--- a/nasal.h
+++ b/nasal.h
@@ -113,11 +113,9 @@ double str2num(const char* str)
 */
 std::string num2str(double number)
 {
-	std::string res;
-	std::stringstream ss;
+	std::ostringstream ss;
 	ss<<number;
-	ss>>res;
-	return res;
+	return ss.str();
 }
 #include "nasal_lexer.h"
 #include "nasal_ast.h"
diff --git a/nasal_builtin.h b/nasal_builtin.h
index 04dafe6..882d7e2 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -199,7 +199,7 @@ nasal_val* builtin_sleep(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
         return nullptr;
     }
     // sleep in unistd.h will make this progress sleep sleep_time seconds.
-    sleep((unsigned long)val_addr->ptr.num);
+    sleep((unsigned int)val_addr->ptr.num);
     return gc.nil_addr;
 }
 
@@ -628,9 +628,7 @@ nasal_val* builtin_contains(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
         builtin_err("contains","\"key\" must be string");
         return nullptr;
     }
-    nasal_val* ret_addr=gc.gc_alloc(vm_num);
-    ret_addr->ptr.num=hash_addr->ptr.hash->elems.count(*key_addr->ptr.str);
-    return ret_addr;
+    return hash_addr->ptr.hash->elems.count(*key_addr->ptr.str)?gc.one_addr:gc.zero_addr;
 }
 nasal_val* builtin_delete(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
 {
@@ -810,6 +808,24 @@ nasal_val* builtin_cmp(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
 }
 nasal_val* builtin_chr(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
 {
+    const char* extend[]={
+        "€"," ","‚","ƒ","„","…","†","‡",
+        "ˆ","‰","Š","‹","Œ"," ","Ž"," ",
+        " ","‘","’","“","”","•","–","—",
+        "˜","™","š","›","œ"," ","ž","Ÿ",
+        " ","¡","¢","£","¤","¥","¦","§",
+        "¨","©","ª","«","¬"," ","®","¯",
+        "°","±","²","³","´","µ","¶","·",
+        "¸","¹","º","»","¼","½","¾","¿",
+        "À","Á","Â","Ã","Ä","Å","Æ","Ç",
+        "È","É","Ê","Ë","Ì","Í","Î","Ï",
+        "Ð","Ñ","Ò","Ó","Ô","Õ","Ö","×",
+        "Ø","Ù","Ú","Û","Ü","Ý","Þ","ß",
+        "à","á","â","ã","ä","å","æ","ç",
+        "è","é","ê","ë","ì","í","î","ï",
+        "ð","ñ","ò","ó","ô","õ","ö","÷",
+        "ø","ù","ú","û","ü","ý","þ","ÿ"
+    };
     nasal_val* code_addr=local_scope[1];
     if(code_addr->type!=vm_num)
     {
@@ -817,7 +833,13 @@ nasal_val* builtin_chr(std::vector<nasal_val*>& local_scope,nasal_gc& gc)
         return nullptr;
     }
     nasal_val* ret_addr=gc.gc_alloc(vm_str);
-    *ret_addr->ptr.str=(char)code_addr->ptr.num;
+    int num=code_addr->ptr.num;
+    if(0<=num && num<128)
+        *ret_addr->ptr.str=(char)num;
+    else if(128<=num && num<256)
+        *ret_addr->ptr.str=extend[num-128];
+    else
+        *ret_addr->ptr.str=" ";
     return ret_addr;
 }
 
diff --git a/nasal_parse.h b/nasal_parse.h
index 248e3ad..3779c4c 100644
--- a/nasal_parse.h
+++ b/nasal_parse.h
@@ -161,12 +161,8 @@ void nasal_parse::match(int type,std::string err_info)
             return;
         }
         std::string s="";
-        for(int i=0;token_table[i].str;++i)
-            if(token_table[i].tok_type==type)
-            {
-                s=token_table[i].str;
-                break;
-            }
+        if(type>=tok_for)// token_table begins at tok_for
+            s=token_table[type-tok_for].str;
         switch(type)
         {
             case tok_num:die(error_line,"expected number");    break;
@@ -391,8 +387,7 @@ nasal_ast nasal_parse::args_gen()
     match(tok_lcurve);
     while(tok_list[ptr].type!=tok_rcurve)
     {
-        nasal_ast tmp;
-        tmp=id_gen();
+        nasal_ast tmp=id_gen();
         match(tok_id);
         if(tok_list[ptr].type==tok_eq || tok_list[ptr].type==tok_ellipsis)
         {
diff --git a/stl/lib.nas b/stl/lib.nas
index c1b031d..8de85cc 100644
--- a/stl/lib.nas
+++ b/stl/lib.nas
@@ -1,28 +1,23 @@
 var import=func(filename)
 {
-    __builtin_import(filename);
-    return nil;
+    return __builtin_import(filename);
 }
-var print=func(elements...)
+var print=func(elems...)
 {
-    __builtin_std_cout(elements);
-    return nil;
+    return __builtin_std_cout(elems);
 };
-var println=func(elements...)
+var println=func(elems...)
 {
-    __builtin_std_cout(elements);
-    print('\n');
-    return nil;
+    __builtin_std_cout(elems);
+    return print('\n');
 }
-var append=func(vector,elements...)
+var append=func(vec,elems...)
 {
-    __builtin_push_back(vector,elements);
-    return nil;
+    return __builtin_push_back(vec,elems);
 }
-var setsize=func(vector,size)
+var setsize=func(vec,size)
 {
-    __builtin_set_size(vector,size);
-    return nil;
+    return __builtin_set_size(vec,size);
 }
 var system=func(str)
 {
@@ -34,36 +29,35 @@ var input=func()
 }
 var sleep=func(duration)
 {
-    __builtin_sleep(duration);
-    return;
+    return __builtin_sleep(duration);
 }
-var split=func(delimeter,string)
+var split=func(deli,str)
 {
-    return __builtin_split(delimeter,string);
+    return __builtin_split(deli,str);
 }
 var rand=func(seed=nil)
 {
     return __builtin_rand(seed);
 }
-var id=func(thing)
+var id=func(object)
 {
-    return __builtin_get_id(thing);
+    return __builtin_get_id(object);
 }
-var int=func(value)
+var int=func(val)
 {
-    return __builtin_int(value);
+    return __builtin_int(val);
 }
-var num=func(value)
+var num=func(val)
 {
-    return __builtin_num(value);
+    return __builtin_num(val);
 }
-var pop=func(vector)
+var pop=func(vec)
 {
-    return __builtin_pop_back(vector);
+    return __builtin_pop_back(vec);
 }
-var str=func(number)
+var str=func(num)
 {
-    return __builtin_str(number);
+    return __builtin_str(num);
 }
 var size=func(object)
 {
@@ -75,8 +69,7 @@ var contains=func(hash,key)
 }
 var delete=func(hash,key)
 {
-    __builtin_delete(hash,key);
-    return;
+    return __builtin_delete(hash,key);
 }
 var keys=func(hash)
 {
@@ -88,49 +81,41 @@ var time=func(begin_time)
 }
 var die=func(str)
 {
-    __builtin_die(str);
-    return nil;
+    return __builtin_die(str);
 }
 var typeof=func(object)
 {
     return __builtin_type(object);
 }
-var substr=func(str,begin,length)
+var substr=func(str,begin,len)
 {
-    return __builtin_substr(str,begin,length);
+    return __builtin_substr(str,begin,len);
 }
 var streq=func(a,b)
 {
     return __builtin_streq(a,b);
 }
-var left=func(string,length)
+var left=func(str,len)
 {
-    return __builtin_left(string,length);
+    return __builtin_left(str,len);
 }
-var right=func(string,length)
+var right=func(str,len)
 {
-    return __builtin_right(string,length);
+    return __builtin_right(str,len);
 }
 var cmp=func(a,b)
 {
     return __builtin_cmp(a,b);
 }
-var chr=func(code) #//Unlike in FG, this chr does not support Extended ASCII
+var chr=func(code)
 {
     return __builtin_chr(code);
 }
 
 var io=
 {
-    fin:func(filename)
-    {
-        return __builtin_fin(filename);
-    },
-    fout:func(filename,str)
-    {
-        __builtin_fout(filename,str);
-        return;
-    }
+    fin: func(filename){return __builtin_fin(filename);},
+    fout:func(filename,str){return __builtin_fout(filename,str);}
 };
 
 var bits=
diff --git a/test/bf.nas b/test/bf.nas
index 43f13e8..8b1a4b4 100644
--- a/test/bf.nas
+++ b/test/bf.nas
@@ -146,16 +146,13 @@ var mandelbrot=
 >>>]>[-]+<]]+>[-<[>>>>>>>>>]<<<<<<<<]>>>>>>>>]<<<<<<<<<[<<<<<<<<<]>>>>[-]<<<++++
 +[-[->>>>>>>>>+<<<<<<<<<]>>>>>>>>>]>>>>>->>>>>>>>>>>>>>>>>>>>>>>>>>>-<<<<<<[<<<<
 <<<<<]]>>>]";
-var hello=
-"++[>++<-]>[>++<-]>[>++<-]>[>++<-]>[>++<-]>+++++++++++++++++++++++++++++++++++++
-+++.---.+++++++..+++.<.>++++++++.--------.+++.------.--------.";
 
 var bf=func(program)
 {
     var paper=[];
     setsize(paper,131072);
-    for(var i=0;i<131072;i+=1)
-        paper[i]=0;
+    #for(var i=0;i<131072;i+=1)
+    #    paper[i]=0;
     var ptr=0;
     var s=program;
     var len=size(s);
@@ -243,16 +240,10 @@ var bf=func(program)
             paper[ptr]=input()[0];
         elsif(code[i][0]==out)
             print(chr(paper[ptr]));
-        elsif(code[i][0]==jt)
-        {
-            if(paper[ptr])
-                i=code[i][1]-1;
-        }
-        elsif(code[i][0]==jf)
-        {
-            if(!paper[ptr])
-                i=code[i][1]-1;
-        }
+        elsif(code[i][0]==jt and paper[ptr])
+            i=code[i][1]-1;
+        elsif(code[i][0]==jf and !paper[ptr])
+            i=code[i][1]-1;
     }
     print('\n');
     return;