C++变量声明被视为函数声明

Question

这个问题是相当理论化的,尽管有趣的是,MS VS2010会main像处理函数声明一样处理以下变量声明(内部):

typedef std::shared_ptr<asymm::PrivateKey> PrivateKeyPtr;

...
void main()
{
    ...
    maidsafe::dht::PrivateKeyPtr pk(); // I'm trying to init variable here, though it thinks it's function declaration

    kNode->node()->Store(key, value, "", ttl, pk, std::bind(&StoreCallback, args::_1, key, ttl));
}

它抛出以下异常:

Error   5   error C2664: 'maidsafe::dht::Node::Store' : cannot convert parameter 5 from 'maidsafe::dht::PrivateKeyPtr (__cdecl *)(void)' to 'maidsafe::dht::PrivateKeyPtr'  C:\Projects\MaidSafe-DHT\src\maidsafe\dht\demo\demo_main.cc 286 1   KademliaDemo

虽然以下几行像魅力一样:

maidsafe::dht::PrivateKeyPtr pk = maidsafe::dht::PrivateKeyPtr();

kNode->node()->Store(key, value, "", ttl, pk, std::bind(&StoreCallback, args::_1, key, ttl));

Answer 1

声明它没有():

maidsafe::dht::PrivateKeyPtr pk;

不幸的是,对于提供未初始化值的原始类型,但在C++ 11中,您可以使用以下值进行初始化{}:

maidsafe::dht::PrivateKeyPtr pk{};

有关相关的解析问题,请参阅c ++最烦恼的解析.