Use wxString's empty() when checking if the string is (non-)empty throughout wx.

Instead of constructs such as if "( s.length() )" and "if (s.length() > 0)" use "if ( !s.empty() )" instead. Similarly for "if (s.length() == 0)" or "if ( s.IsNull() )", use "if ( s.empty() )".
No code changes intended except for a few instances where a construct like "if ( s.length() && wxFileExists(s) )" was changed to not check the length of the string and let wxFileExists handle such cases.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66728 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/helpext.cpp

@@ -339,7 +339,7 @@ bool wxExtHelpController::DisplayContents()
     file << m_helpDir << wxFILE_SEP_PATH << contents;
     if (file.Contains(wxT('#')))
         file = file.BeforeLast(wxT('#'));
-    if (contents.length() && wxFileExists(file))
+    if ( wxFileExists(file) )
         rc = DisplaySection(WXEXTHELP_CONTENTS_ID);
 
     // if not found, open homemade toc: