added operator-(const wxChar *, const wxCStrData&) to allow compilation of the code doing "p - s.c_str()" where p is a pointer into the string s

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45290 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/string.h

@@ -2347,6 +2347,22 @@ inline wxUniChar wxCStrData::operator[](size_t n) const
     return m_str->at(m_offset + n);
 }
 
+// ----------------------------------------------------------------------------
+// more wxCStrData operators
+// ----------------------------------------------------------------------------
+
+// we need to define those to allow "size_t pos = p - s.c_str()" where p is
+// some pointer into the string
+inline size_t operator-(const char *p, const wxCStrData& cs)
+{
+    return p - cs.AsChar();
+}
+
+inline size_t operator-(const wchar_t *p, const wxCStrData& cs)
+{
+    return p - cs.AsWChar();
+}
+
 // ----------------------------------------------------------------------------
 // implementation of wx[W]CharBuffer inline methods using wxCStrData
 // ----------------------------------------------------------------------------