PVS-Studio warning V547 for TPP

bool TandemResultsParser::writePepXML(....)
{
  ...
  char c = pathSummary.at(pathSummary.length() - 1);
  if (c != '\\' || c != '/')
  ...
}

This is what should have been written here:
if (c != '\\' && c != '/')

This suspicious code was found in TPP project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'c != '\\' || c != '/'' is always true. Probably the '&&' operator should be used here. Tandem2XML tandemresultsparser.cxx 787

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