c – 为什么此模板在Xcode中有错误而在Visual Studio中没有错误

第一个版本在Xcode中报告错误,但在Visual Studio中报告错误.

// Version 1: Error in Xcode,but not Visual Studio
template<typename LengthT,typename VertexT> 
int MyGraphAlgorithm(...arguments omitted...)
{
  using namespace boost;

  typedef property<vertex_distance_t,LengthT> VertextProperties_t;
  typedef adjacency_list<vecS,vecS,directedS,VertextProperties_t> Graph;
  // In next line Xcode reports: "error: expected `;' before 'vertexInitial'"
  graph_traits<Graph>::vertex_descriptor vertexInitial(100);
}

第二个没有错误.不同之处在于模板化typedef中模板参数LengthT的使用.

// Version 2: No error in Xcode or Visual Studio
template<typename LengthT,typename VertexT> 
int MyGraphAlgorithm(...arguments omitted...)
{
  using namespace boost;

  // In the following line,LengthT has been changed to int
  typedef property<vertex_distance_t,int> VertextProperties_t;
  typedef adjacency_list<vecS,VertextProperties_t> Graph;
  graph_traits<Graph>::vertex_descriptor  vertexInitial(100);
}