g ++错误：预期;在“it”之前。 [英] g++ error: expected ; before "it"

问题描述

我将C ++应用程序从Solaris移植到Linux，并且遇到以下错误。代码是：

I'm porting C++ app from Solaris to Linux and I'm stuck with the following error. The code is:

template <class MapSuperClass> class FWPointerMap : public MapSuperClass
{
  public:
    FWPointerMap()
    {
      _wipe = false;
    }

    FWPointerMap(const MapSuperClass* mMap)
    {
      MapSuperClass::const_iterator it = mMap->begin(); // line 50
      while(it != mMap->end())
      {
        insert(MapSuperClass::value_type((*it).first, (*it).second));
        it++;
      }
      _wipe = false;
    }

我得到以下错误：

And I get the following error:

../../framework/fwcore/hdr/FWPointerMap: In constructor FWPointerMap<MapSuperClass>::FWPointerMap(const MapSuperClass*):
../../framework/fwcore/hdr/FWPointerMap:50: error: expected ; before it
../../framework/fwcore/hdr/FWPointerMap:52: error: it was not declared in this scope

推荐答案

我想你只需要添加'typename'来告诉编译器MapSuperClass :: const_iterator是一个类型：

I think you just need to add 'typename' to tell the compiler that MapSuperClass::const_iterator is a type:

typename MapSuperClass::const_iterator it = mMap->begin(); // line 50

因为MaySuperClass是类模板参数，所以假设const_iterator成员是领域。使用 typename 通知编译器它实际上是一个类型。

Because MaySuperClass is a class template parameter, the assumption is that the const_iterator member is a field. Using typename informs the compiler that it is in fact a type.

更多信息： http://en.wikipedia.org/wiki/Typename#A_method_for_indicating_that_a_dependent_name_is_a_type

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