--- esN.py-	2016-09-08 02:20:00.000000000 +0900
+++ esN.py	2016-09-08 03:00:00.000000000 +0900
@@ -197,6 +197,12 @@ def tree_kwd(lst, kdic):
 			if top_is(r, 'kwd', 'else'):
 				e += [ r.pop(0)[2] ]
 			return [ e ] + r
+		if v == 'while' and len( lst[2:] ) > 0:
+			if lst[1][:2] != [ 'br_s', '(' ]:
+				err_exit("not found '(' after 'while'")
+			r = tree_kwd( lst[2:], kdic )
+			e = [ k, v, lst[1], r.pop(0) ]
+			return [ e ] + r
 	e = e[:2] + tree_kwd( e[2:], kdic )
 	return step(e, 1)
 
@@ -253,7 +259,7 @@ def es_split(s):
 		'br_e' : [ ')', ']', '}' ],
 		'op' : ops_flat,
 		'type' : [ 'int', 'char', 'void' ],
-		'kwd' : [ 'return', 'if', 'else' ],
+		'kwd' : [ 'return', 'if', 'else', 'while' ],
 		'spc' : [ ' ', '\t', '\n' ],
 		'etc' : [ ';', ',' ],
 	}
@@ -340,6 +346,16 @@ def do_op2(v, a, b, info):
 		return a / b
 	if v == '==':
 		return a == b
+	if v == '!=':
+		return a != b
+	if v == '<=':
+		return a <= b
+	if v == '<':
+		return a < b
+	if v == '>=':
+		return a >= b
+	if v == '>':
+		return a > b
 
 	warn_no_sup('do_op2', 'v', v)
 
@@ -366,21 +382,30 @@ def do_arr(name, idx, info):
 	get_env(info)[name] = [ None ] * i  # new
 	return None
 
+def do_kwd(v, expr, info):
+	if v == 'return':
+		r = do_expr( expr[2], info )
+		get_call_inf(info)['ret'] = r
+		return None
+	if v == 'if':
+		if do_expr( expr[2], info ):
+			do_expr( expr[3], info )
+		elif len(expr) > 4:
+			do_expr( expr[4], info )
+		return None
+	if v == 'while':
+		while do_expr( expr[2], info ):
+			do_expr( expr[3], info )
+		return None
+
+	warn_no_sup('do_kwd', 'v', v)
+
 def do_expr(expr, info):
 	if info.get('verb') >= 2:
 		print('expr={}'.format(expr))
 	(k, v) = expr[:2]
 	if k == 'kwd':
-		if v == 'return':
-			r = do_expr( expr[2], info )
-			get_call_inf(info)['ret'] = r
-			return None
-		if v == 'if':
-			if do_expr( expr[2], info ):
-				do_expr( expr[3], info )
-			elif len(expr) > 4:
-				do_expr( expr[4], info )
-			return None
+		return do_kwd(v, expr, info)
 	if k == 'num':
 		return float(v)
 	if k == 'str':
@@ -388,8 +413,12 @@ def do_expr(expr, info):
 	if k == 'name':
 		return get_env(info).get(v)
 	if k == 'br_s':
-		e = expr[2][0]
-		return do_expr(e, info)
+		if v == '(':
+			e = expr[2][0]
+			return do_expr(e, info)
+		if v == '{':
+			do_blk(expr, info)
+			return None
 	if k == 'op':
 		return do_op( v, expr[2:], info )
 	if k == 'arr':