diff --git a/examples/str.php b/examples/str.php
new file mode 100644
index 00000000..ab2b3a25
--- /dev/null
+++ b/examples/str.php
@@ -0,0 +1,5 @@
+<?php
+$s = '123';
+$key = new stdClass();
+var_dump(isset($s[true]));
+var_dump($s[$key]);