Simple questions again

[sedawk]

Hi,

Here are some basic VC++ questions I have while I am learning it:

1. BOOL APIENTRY DllMain()

I don't know if it is necessary to have APIENTRY keyword and the name "DllMain" is fixed. Can I use other name such as "DLLMAIN"?

2. std::string str
I couldn't find the MSDN definition about this type declaration when I highlighted it and press F1. What property of std has? what is the difference between std::string str and,
string str?

3. CCaptureFrame::CCaptureFrame()
: CWindowImpl <CCaptureFrame> (),
m_hVfwWnd(NULL),
m_bPreview(false),
m_bStretch(false),
m_bProportional(false),
m_pFormat(NULL),
m_hIC(NULL),
m_dwFrames(0)

From the above declaration, I know the first line is a derived class method(function) by double colon. But what does the second line the single colon mean here? Within the carat &quot;CCapturFrame&quot; means what? Can I use something like:

CCaptureFrameublic CWindwoImpl

for the second line?

Thanks.

 

[SeekerOfKnowledge]

two answers :
2. std is a namespace, something like a pacjage in ADA (if
you know this language). It is an area of code that
encapsulates type definitions, variables, etc. You can omit
the &quot;std::&quot; prefix by s &quot;use&quot; statement as follows:
using namespace std;
at the begining of your code segment.
string is simply a class (type) declared withing the std namespace
3.The caret identifies the CWindowImpl class as a template class. A template is a generic class that can accept one or more arguments that modify it's behaviour. Read about those in any C++ book. The notation of a colon in a constructor class designates a call to a base class constructor, so if

class AClass : public Class BaseClass
and the constructor of AClass receives a parameter that has
to passed on to the base class, the notaion is

ClassA::ClassA(Param):BaseClass(Param)
{
//Some Code
}

Another reason to use this notation, even withou parameters
to the CTOR is if the base class is a template, like the
example you brought, when the CTOR call the instantiated
CTOR of the Base clas with the desired Template parameter.

Good Luck
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SeekerOfKnowledge
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