made ptrdiff_t visible to GCC 4.6 compiler

diff --git a/modules/core/include/opencv2/core/core.hpp b/modules/core/include/opencv2/core/core.hpp
index ca1dd3e..7bf76e1 100644 (file)
--- a/modules/core/include/opencv2/core/core.hpp
+++ b/modules/core/include/opencv2/core/core.hpp
@@ -75,6 +75,7 @@ namespace cv {
 
 using std::vector;
 using std::string;
+using std::ptrdiff_t;
     
 template<typename _Tp> class CV_EXPORTS Size_;
 template<typename _Tp> class CV_EXPORTS Point_;