From ddee605f8f20617be9361bc355b4a98a66623edc Mon Sep 17 00:00:00 2001
From: Liu Ming <extrafliu@gmail.com>
Date: Fri, 30 Oct 2015 16:01:42 +0800
Subject: [PATCH] fix the xf error

---
 col.go | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/col.go b/col.go
index 7717529..b82d175 100644
--- a/col.go
+++ b/col.go
@@ -43,11 +43,13 @@ type XfRk struct {
 }
 
 func (xf *XfRk) String(wb *WorkBook) string {
-	switch wb.Xfs[21].formatNo() {
-	case 27:
-		if f, e := xf.Rk.Float(); e == nil {
-			t := timeFromExcelTime(f, true)
-			return t.Format("2006.01") //TODO it should be international
+	if len(wb.Xfs) > 21 {
+		switch wb.Xfs[21].formatNo() {
+		case 27:
+			if f, e := xf.Rk.Float(); e == nil {
+				t := timeFromExcelTime(f, true)
+				return t.Format("2006.01") //TODO it should be international
+			}
 		}
 	}
 	return fmt.Sprintf("%s", xf.Rk.String())