From 4cf742902d921de85cc405e51e28d35ce4b5985a Mon Sep 17 00:00:00 2001
From: otya128 <otya128@users.noreply.github.com>
Date: Tue, 20 Dec 2016 21:40:11 +0900
Subject: [PATCH] Fix INSTR

---
 SMILEBASIC/builtinfunctions.d | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/SMILEBASIC/builtinfunctions.d b/SMILEBASIC/builtinfunctions.d
index 978b675..1ac07b6 100644
--- a/SMILEBASIC/builtinfunctions.d
+++ b/SMILEBASIC/builtinfunctions.d
@@ -1228,7 +1228,11 @@ class BuiltinFunction
             str1 = vstart.castDString;
             str2 = vstr1.castDString;
         }
-        return cast(int)(str1[start..$].indexOf(str2, CaseSensitive.no));
+        ptrdiff_t index = str1[start..$].indexOf(str2);
+        if (index == -1)
+            return -1;
+        else
+            return cast(int)(index + start);
     }
     static int ASC(wstring str)
     {