windows 什么时候返回 E_POINTER，什么时候返回 E_INVALIDARG？
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When return E_POINTER and when E_INVALIDARG?
提问by sharptooth
COM interfaces methods can return various HRESULTvalues to signal invalid argument values passed. When do I return E_POINTERand when E_INVALIDARG?
COM 接口方法可以返回各种HRESULT值来表示传递的无效参数值。我什么E_POINTER时候回来，什么时候回来E_INVALIDARG？
As I understand if a method receives an index in an encapsulated collection and it is out of bounds that is E_INVALIDARG. If a method receives an Interface**pointer where it is meant to store a pointer to a newly created object that's E_POINTER.
据我了解，如果一个方法在封装的集合中接收一个索引并且它超出了E_INVALIDARG. 如果一个方法接收到一个Interface**指针，用于存储指向新创建的对象的指针，该对象是E_POINTER.
HRESULT CImpl::GetItem( long index; Interface** result )
{
if( result == 0 ) {
return E_POINTER;
}
if( index < 0 || index >= internalArray.size() ) {
return E_INVALIDARG;
}
*result = CreateWrapperObject( internalArray[index] );
return S_OK;
}
But what if it receives a WCHAR*buffer with a file name as an "in" parameter and this WCHAR*is null? Is this E_POINTERor E_INVALIDARG?
但是如果它接收一个WCHAR*带有文件名作为“in”参数的缓冲区并且它WCHAR*是空的呢？这是E_POINTER还是E_INVALIDARG？
Or a method receives a pointer to some struct and is expected to fill the struct through that pointer and this pointer is null - is this E_POINTERor E_INVALIDARG?
或者一个方法接收一个指向某个结构的指针，并期望通过该指针填充该结构并且该指针为空 - 这是E_POINTER还是E_INVALIDARG？
HRESULT CImpl::SaveToFile( WCHAR* fileName )
{
if( fileName == 0 ) {
return // what to return here?
}
//... do actual work here
}
HRESULT CImpl::GetAttributes( Attributes* to )
{
if( to == 0 ) {
return // what to return here?
}
attributes->IsCool = getIsCool();
attributes->Color = RGB( 0, 255, 0 );
return S_OK;
}
What are the rules for when to return E_POINTERand when E_INVALIDARGwhen checking pointer type parameters?
何时返回E_POINTER以及E_INVALIDARG何时检查指针类型参数的规则是什么？
回答by Shay Erlichmen
You return E_POINTERwhen the reference to the pointer of an outparameter is null, this consider to be an error code that indicates a bug in the program or in the interop layer.
返回E_POINTER时，引用到的指针出参数为空，这样认为是一个错误代码，指明在程序或在互操作层的错误。
You return E_INVALIDARGwhen there is an application level on with the parameter for example out of range issue or parameter that collide with each other.
E_INVALIDARG当应用程序级别与参数（例如超出范围的问题或相互冲突的参数）时，您将返回。
In Your case, in SaveToFile(...)you should return E_INVLIADARGsince it is not valid to pass empty file name, and in GetAttributes(...)you should return E_POINTER(if it's an out param) because you cannot fill the value.
在您的情况下，SaveToFile(...)您应该返回，E_INVLIADARG因为传递空文件名无效，并且GetAttributes(...)您应该返回E_POINTER（如果它是一个 out 参数），因为您无法填充该值。
And yes, we all L-O-V-E com :)
是的，我们都喜欢 com :)
