Hello, dear all,
I often see these two import usage in the code. Both are the interface
to use the Dll library. I think they are the same.
Normally P/Invoke means using the [DllImport ....] to import the
dll. But I have some confusion about them.
1. Is the "_declspec(dlli mport)" also one of the forms of P/Invoke?
2. From performance aspect, which way is more better?
3. What's the difference of them.
Thank you in advance!
2  3672 
Ed wrote:
Hello, dear all,
I often see these two import usage in the code. Both are the interface
to use the Dll library. I think they are the same.
Normally P/Invoke means using the [DllImport ....] to import the
dll. But I have some confusion about them.
1. Is the "_declspec(dlli mport)" also one of the forms of P/Invoke?
No. __declspec(dlli mport) is a compiler directive that tells the compiler to
expect that the function so decorated will be satisfied by an import library
to be linked into the module. [DllImportAttrib ute] is a CLR attribute used
in managed (.NET) development that provides the mapping for P/Invoke to call
an external function. They're similar, it's true, but the first
(__declspec) has nothing to do with managed programming.
2. From performance aspect, which way is more better?
They're used for different purposes. If you have a choice (e.g. you're
writing managed C++), __declspec(dlli mport) will never give worse
performance.
3. What's the difference of them.
See above.
-cd
On Jul 30, 9:35 pm, "Carl Daniel [VC++ MVP]"
<cpdaniel_remov e_this_and_nos. ..@mvps.org.nos pamwrote:
Ed wrote:
Hello, dear all,
I often see these two import usage in the code. Both are the interface
to use the Dll library. I think they are the same.
Normally P/Invoke means using the [DllImport ....] to import the
dll. But I have some confusion about them.
1. Is the "_declspec(dlli mport)" also one of the forms of P/Invoke?
No. __declspec(dlli mport) is a compiler directive that tells the compiler to
expect that the function so decorated will be satisfied by an import library
to be linked into the module. [DllImportAttrib ute] is a CLR attribute used
in managed (.NET) development that provides the mapping for P/Invoke to call
an external function. They're similar, it's true, but the first
(__declspec) has nothing to do with managed programming.
2. From performance aspect, which way is more better?
They're used for different purposes. If you have a choice (e.g. you're
writing managed C++), __declspec(dlli mport) will never give worse
performance.
3. What's the difference of them.
See above.
-cd
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