diff --git a/qse/lib/awk/misc.c b/qse/lib/awk/misc.c
index 52ccfd5e..e9f8f095 100644
--- a/qse/lib/awk/misc.c
+++ b/qse/lib/awk/misc.c
@@ -1,5 +1,5 @@
 /*
- * $Id: misc.c 510 2011-07-20 16:17:16Z hyunghwan.chung $
+ * $Id: misc.c 514 2011-07-22 15:37:46Z hyunghwan.chung $
  *
     Copyright 2006-2011 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -1108,3 +1108,36 @@ void qse_awk_rtx_freemem (qse_awk_rtx_t* rtx, void* ptr)
 	qse_awk_freemem (rtx->awk, ptr);
 }
 
+int qse_awk_sprintlong (
+	qse_awk_t* awk, qse_char_t* buf, qse_size_t len, qse_long_t num)
+{
+	return awk->prm.sprintf (
+		awk, buf, len,
+	#if QSE_SIZEOF_LONG_LONG > 0
+		QSE_T("%lld"), (long long)num
+	#elif QSE_SIZEOF___INT64 > 0
+		QSE_T("%I64d"), (__int64)num
+	#elif QSE_SIZEOF_LONG > 0
+		QSE_T("%ld"), (long)num
+	#elif QSE_SIZEOF_INT > 0
+		QSE_T("%d"), (int)num
+	#else
+		#error unsupported size	
+	#endif
+	);
+}
+
+int qse_awk_sprintreal (
+	qse_awk_t* awk, qse_char_t* buf, qse_size_t len, qse_real_t num)
+{
+	return awk->prm.sprintf (
+		awk, buf, len,
+	#if QSE_SIZEOF_LONG_DOUBLE > 0
+		QSE_T("%Lf"), (long long)num
+	#elif QSE_SIZEOF_DOUBLE > 0
+		QSE_T("%f"), (double)num
+	#else
+		#error unsupported size	
+	#endif
+	);
+}
diff --git a/qse/lib/awk/misc.h b/qse/lib/awk/misc.h
index 998aa594..633346f5 100644
--- a/qse/lib/awk/misc.h
+++ b/qse/lib/awk/misc.h
@@ -1,5 +1,5 @@
 /*
- * $Id: misc.h 462 2011-05-18 14:36:40Z hyunghwan.chung $
+ * $Id: misc.h 514 2011-07-22 15:37:46Z hyunghwan.chung $
  *
     Copyright 2006-2011 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -76,6 +76,22 @@ int qse_awk_matchrex (
 	qse_cstr_t* match, qse_awk_errnum_t* errnum
 );
 
+int qse_awk_sprintlong (
+     qse_awk_t*  awk, 
+	qse_char_t* buf,
+	qse_size_t  len,
+	qse_long_t  num
+);
+
+
+int qse_awk_sprintreal (
+	qse_awk_t*  awk,
+	qse_char_t* buf,
+	qse_size_t  len,
+	qse_real_t  num
+);
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/qse/lib/awk/parse.c b/qse/lib/awk/parse.c
index 6a87c0d7..df09e616 100644
--- a/qse/lib/awk/parse.c
+++ b/qse/lib/awk/parse.c
@@ -1,5 +1,5 @@
 /*
- * $Id: parse.c 486 2011-05-29 15:22:08Z hyunghwan.chung $
+ * $Id: parse.c 514 2011-07-22 15:37:46Z hyunghwan.chung $
  *
     Copyright 2006-2011 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -3351,6 +3351,8 @@ static qse_awk_nde_t* parse_binary (
 		qse_awk_loc_t rloc;
 		const binmap_t* p = binmap;
 		qse_bool_t matched = QSE_FALSE;
+		int fold;
+		qse_long_t folded_l;
 
 		while (p->token != TOK_EOF)
 		{
@@ -3382,24 +3384,70 @@ static qse_awk_nde_t* parse_binary (
 			return QSE_NULL;
 		}
 
-		nde = (qse_awk_nde_exp_t*) QSE_AWK_ALLOC (
-			awk, QSE_SIZEOF(qse_awk_nde_exp_t));
-		if (nde == QSE_NULL) 
+		fold = 0;
+		if (left->type == QSE_AWK_NDE_INT &&
+		    right->type == QSE_AWK_NDE_INT)
 		{
-			qse_awk_clrpt (awk, right);
-			qse_awk_clrpt (awk, left);
-			SETERR_LOC (awk, QSE_AWK_ENOMEM, xloc);
-			return QSE_NULL;
+			fold = 1;
+			switch (opcode)
+			{
+				case QSE_AWK_BINOP_PLUS:
+					folded_l = ((qse_awk_nde_int_t*)left)->val + ((qse_awk_nde_int_t*)right)->val;
+					break;
+
+				case QSE_AWK_BINOP_MINUS:
+					folded_l = ((qse_awk_nde_int_t*)left)->val - ((qse_awk_nde_int_t*)right)->val;
+					break;
+
+				case QSE_AWK_BINOP_MUL:
+					folded_l = ((qse_awk_nde_int_t*)left)->val * ((qse_awk_nde_int_t*)right)->val;
+					break;
+
+				case QSE_AWK_BINOP_IDIV:
+					folded_l = ((qse_awk_nde_int_t*)left)->val / ((qse_awk_nde_int_t*)right)->val;
+					break;
+
+				case QSE_AWK_BINOP_MOD:
+					folded_l = ((qse_awk_nde_int_t*)left)->val % ((qse_awk_nde_int_t*)right)->val;
+					break;
+
+				default:
+					fold = 0;
+			}
 		}
 
-		nde->type = QSE_AWK_NDE_EXP_BIN;
-		nde->loc = *xloc;
-		nde->next = QSE_NULL;
-		nde->opcode = opcode; 
-		nde->left = left;
-		nde->right = right;
+		if (fold)
+		{
+			qse_awk_clrpt (awk, right);
+			((qse_awk_nde_int_t*)left)->val = folded_l;
+			if (((qse_awk_nde_int_t*)left)->str)
+			{
+				QSE_AWK_FREE (awk, ((qse_awk_nde_int_t*)left)->str);
+				((qse_awk_nde_int_t*)left)->str = QSE_NULL;
+				((qse_awk_nde_int_t*)left)->len = 0;
+			}
+		}
+		else
+		{
+			nde = (qse_awk_nde_exp_t*) QSE_AWK_ALLOC (
+				awk, QSE_SIZEOF(qse_awk_nde_exp_t));
+			if (nde == QSE_NULL) 
+			{
+				qse_awk_clrpt (awk, right);
+				qse_awk_clrpt (awk, left);
+				SETERR_LOC (awk, QSE_AWK_ENOMEM, xloc);
+				return QSE_NULL;
+			}
 
-		left = (qse_awk_nde_t*)nde;
+			nde->type = QSE_AWK_NDE_EXP_BIN;
+			nde->loc = *xloc;
+			nde->next = QSE_NULL;
+			nde->opcode = opcode; 
+			nde->left = left;
+			nde->right = right;
+
+			left = (qse_awk_nde_t*)nde;
+		}
 	}
 
 	return left;
@@ -3612,13 +3660,13 @@ static qse_awk_nde_t* parse_concat (
 			}
 		}
 		else if (MATCH(awk,TOK_LPAREN) ||
-	                 MATCH(awk,TOK_DOLLAR) ||
-			 MATCH(awk,TOK_PLUS) ||
-			 MATCH(awk,TOK_MINUS) ||
-			 MATCH(awk,TOK_PLUSPLUS) ||
-			 MATCH(awk,TOK_MINUSMINUS) ||
-			 MATCH(awk,TOK_LNOT) ||
-			 awk->tok.type >= TOK_GETLINE)
+		         MATCH(awk,TOK_DOLLAR) ||
+		         MATCH(awk,TOK_PLUS) ||
+		         MATCH(awk,TOK_MINUS) ||
+		         MATCH(awk,TOK_PLUSPLUS) ||
+		         MATCH(awk,TOK_MINUSMINUS) ||
+		         MATCH(awk,TOK_LNOT) ||
+		         awk->tok.type >= TOK_GETLINE)
 		{
 			/* TODO: is the check above sufficient? */
 			if (!(awk->option & QSE_AWK_IMPLICIT)) break;
@@ -3692,6 +3740,8 @@ static qse_awk_nde_t* parse_unary (
 	qse_awk_nde_t* left;
 	qse_awk_loc_t uloc;
 	int opcode;
+	int fold;
+	qse_long_t folded_l;
 
 	opcode = (MATCH(awk,TOK_PLUS))?  QSE_AWK_UNROP_PLUS:
 	         (MATCH(awk,TOK_MINUS))? QSE_AWK_UNROP_MINUS:
@@ -3717,23 +3767,68 @@ static qse_awk_nde_t* parse_unary (
 	awk->parse.depth.cur.expr--;
 	if (left == QSE_NULL) return QSE_NULL;
 
-	nde = (qse_awk_nde_exp_t*) 
-		QSE_AWK_ALLOC (awk, QSE_SIZEOF(qse_awk_nde_exp_t));
-	if (nde == QSE_NULL)
+	fold = 0;
+	if (left->type == QSE_AWK_NDE_INT)
 	{
-		qse_awk_clrpt (awk, left);
-		SETERR_LOC (awk, QSE_AWK_ENOMEM, xloc);
-		return QSE_NULL;
+		fold = 1;
+
+		switch (opcode)
+		{
+			case QSE_AWK_UNROP_PLUS:
+				folded_l = ((qse_awk_nde_int_t*)left)->val;
+				break;
+
+			case QSE_AWK_UNROP_MINUS:
+				folded_l = -((qse_awk_nde_int_t*)left)->val;
+				break;
+
+			case QSE_AWK_UNROP_LNOT:
+				folded_l = !((qse_awk_nde_int_t*)left)->val;
+				break;
+
+			case QSE_AWK_UNROP_BNOT:
+				folded_l = ~((qse_awk_nde_int_t*)left)->val;
+				break;
+
+			default:
+				fold = 0;
+				break;
+		}
 	}
 
-	nde->type = QSE_AWK_NDE_EXP_UNR;
-	nde->loc = *xloc;
-	nde->next = QSE_NULL;
-	nde->opcode = opcode;
-	nde->left = left;
-	nde->right = QSE_NULL;
+	if (fold)
+	{
+		((qse_awk_nde_int_t*)left)->val = folded_l;
+		if (((qse_awk_nde_int_t*)left)->str)
+		{
+			QSE_AWK_FREE (awk, ((qse_awk_nde_int_t*)left)->str);
+			((qse_awk_nde_int_t*)left)->str = QSE_NULL;
+			((qse_awk_nde_int_t*)left)->len = 0;
+		}
+
+		return left;
+	}
+	else
+	{
+		nde = (qse_awk_nde_exp_t*) 
+			QSE_AWK_ALLOC (awk, QSE_SIZEOF(qse_awk_nde_exp_t));
+		if (nde == QSE_NULL)
+		{
+			qse_awk_clrpt (awk, left);
+			SETERR_LOC (awk, QSE_AWK_ENOMEM, xloc);
+			return QSE_NULL;
+		}
+
+		nde->type = QSE_AWK_NDE_EXP_UNR;
+		nde->loc = *xloc;
+		nde->next = QSE_NULL;
+		nde->opcode = opcode;
+		nde->left = left;
+		nde->right = QSE_NULL;
+
+		return (qse_awk_nde_t*)nde;
+	}
 
-	return (qse_awk_nde_t*)nde;
 }
 
 static qse_awk_nde_t* parse_exponent (
diff --git a/qse/lib/awk/run.c b/qse/lib/awk/run.c
index 12bf2cc2..3780c541 100644
--- a/qse/lib/awk/run.c
+++ b/qse/lib/awk/run.c
@@ -1,5 +1,5 @@
 /*
- * $Id: run.c 485 2011-05-29 15:15:52Z hyunghwan.chung $
+ * $Id: run.c 514 2011-07-22 15:37:46Z hyunghwan.chung $
  *
     Copyright 2006-2011 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -6822,22 +6822,12 @@ qse_char_t* qse_awk_rtx_format (
 
 			do
 			{
-				n = rtx->awk->prm.sprintf (
+				n = qse_awk_sprintlong (
 					rtx->awk,
 					rtx->format.tmp.ptr,
 					rtx->format.tmp.len,
-				#if QSE_SIZEOF_LONG_LONG > 0
-					QSE_T("%lld"), (long long)width
-				#elif QSE_SIZEOF___INT64 > 0
-					QSE_T("%I64d"), (__int64)width
-				#elif QSE_SIZEOF_LONG > 0
-					QSE_T("%ld"), (long)width
-				#elif QSE_SIZEOF_INT > 0
-					QSE_T("%d"), (int)width
-				#else
-					#error unsupported size	
-				#endif
-					);
+					width
+				);
 				if (n == -1)
 				{
 					GROW (&rtx->format.tmp);
diff --git a/qse/lib/awk/tree.c b/qse/lib/awk/tree.c
index bf77691e..afba4d96 100644
--- a/qse/lib/awk/tree.c
+++ b/qse/lib/awk/tree.c
@@ -1,5 +1,5 @@
 /*
- * $Id: tree.c 485 2011-05-29 15:15:52Z hyunghwan.chung $
+ * $Id: tree.c 514 2011-07-22 15:37:46Z hyunghwan.chung $
  *
     Copyright 2006-2011 Chung, Hyung-Hwan.
     This file is part of QSE.
@@ -260,19 +260,39 @@ static int print_expr (qse_awk_t* awk, qse_awk_nde_t* nde)
 
 		case QSE_AWK_NDE_INT:
 		{
-			QSE_ASSERT (((qse_awk_nde_int_t*)nde)->str != QSE_NULL);
-			PUT_SRCSTRX (awk,
-				((qse_awk_nde_int_t*)nde)->str,
-				((qse_awk_nde_int_t*)nde)->len);
+			if (((qse_awk_nde_int_t*)nde)->str)
+			{
+				PUT_SRCSTRX (awk,
+					((qse_awk_nde_int_t*)nde)->str,
+					((qse_awk_nde_int_t*)nde)->len);
+			}
+			else
+			{
+				qse_char_t buf[64];
+				qse_awk_sprintlong (
+					awk, buf, QSE_COUNTOF(buf), 
+					((qse_awk_nde_int_t*)nde)->val);
+				PUT_SRCSTR (awk, buf);
+			}
 			break;
 		}
 
 		case QSE_AWK_NDE_REAL:
 		{
-			QSE_ASSERT (((qse_awk_nde_real_t*)nde)->str != QSE_NULL);
-			PUT_SRCSTRX (awk,
-				((qse_awk_nde_real_t*)nde)->str,
-				((qse_awk_nde_real_t*)nde)->len);
+			if (((qse_awk_nde_real_t*)nde)->str)
+			{
+				PUT_SRCSTRX (awk,
+					((qse_awk_nde_real_t*)nde)->str,
+					((qse_awk_nde_real_t*)nde)->len);
+			}
+			else
+			{
+				qse_char_t buf[64];
+				qse_awk_sprintreal (
+					awk, buf, QSE_COUNTOF(buf), 
+					((qse_awk_nde_real_t*)nde)->val);
+				PUT_SRCSTR (awk, buf);
+			}
 			break;
 		}
 
@@ -1211,7 +1231,7 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 
 			case QSE_AWK_NDE_INT:
 			{
-				if (((qse_awk_nde_int_t*)p)->str != QSE_NULL)
+				if (((qse_awk_nde_int_t*)p)->str)
 					QSE_AWK_FREE (awk, ((qse_awk_nde_int_t*)p)->str);
 				QSE_AWK_FREE (awk, p);
 				break;
@@ -1219,7 +1239,7 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 
 			case QSE_AWK_NDE_REAL:
 			{
-				if (((qse_awk_nde_real_t*)p)->str != QSE_NULL)
+				if (((qse_awk_nde_real_t*)p)->str)
 					QSE_AWK_FREE (awk, ((qse_awk_nde_real_t*)p)->str);
 				QSE_AWK_FREE (awk, p);
 				break;