From C++ to Delphi: several approaches to deal with pointer parameters

I'm writing a piece of code that will interact with a 3rd party C++ library.

In a particular function, for example, the header and function looks like this:
(There are several dozens funcions to call)


SOME_API int CPP_GetSomeValue(int* valueRet);


The function is defined like this:

int CPP_GetSomeValue(int* valueRet);
{
  GetSomeValue(valueRet);
  return 0;
}

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Then the function it calls, is defined like this:

int GetSomeValue(int* valueRet)
{
  int val;
  SomeVal(val)
  *valueRet = val;
  return 0;
}

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and finally SomeVal is defined like this:

int SomeVal(int& typeRet)
{
  typeRet = 255;	
  return 0;
}

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Now, in Delphi, I have my header defined like this:

CPP_GetSomeValue: function (valueRet: PInteger): Integer stdcall;


And finally how should I define and send and get this value back which was filled by the C++

Library?

I found 3 ways to do the same, but I want to know what's the correct way to do it, what are the

difference between them, and possible problems:


1)
The easiest one, just declare an Integer, pass the address, read the value again.

ivalueRet : Integer; 

CPP_GetSomeValue(@ivalueRet);
Result := ivalueRet;

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.. though I feel this "risky", doesn't seem safe. but I don't know



2)
Define a PInteger, New it, pass it, derreference it and dispose it      

pvalueRet : Pinteger;

New(pvalueRet); 
CPP_GetSomeValue(pvalueRet);
Result := pvalueRet^;
Dispose(pvalueRet);

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(I found this also works to get the value: Result := PInteger(@pvalueRet)^;)




3)
Define a PInteger, but don't initialize it and pass the address:

pvalueRet : Pinteger; 
// Not "new", not "dispose"
CPP_GetSomeValue(@pvalueRet);
Result := Integer(pvalueRet);

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(I found this also works to get the value: Result := PInteger(@pvalueRet)^;)

This also looks weird, like I'm just using the pointer to get the integer back.


Which one is the correct? The one that doesn't get me memory leaks, dangling pointers and ugly stuff like that.