diff --git a/str.go b/str.go
index 6e097b2..5fe1e03 100644
--- a/str.go
+++ b/str.go
@@ -16,7 +16,10 @@ const (
 )
 
 // get random number string with length.
-func GetRandomString(l int) string {
+var GetRandomString = GetRandomNumString
+
+// get random number string with length.
+func GetRandomNumString(l int) string {
 	str := NUMBERSTRING
 	bytes := []byte(str)
 	result := []byte{}