C / C++ / MFC

Hamed Mosavi wrote:

If this is the case, it might be possible to write something like this:


myStruct* pStruct = new myStruct(nSize);
where nSize is not equal to sizeof(myStruct);.

Rajkumar R wrote:

alls the overloaded constructor

Rajkumar R wrote:

how you are thinking to use that object as myStruct

Hamed Mosavi wrote:

My question was that, is it possible to get rid of casting and the type specified in new and explicitly define needed size of memory to allocate(and based on the type myStruct) the operator cast the result automatically?

#include<new>
#include<iostream>

using namespace std;

struct myStruct
{
   myStruct( )
   {
      cout << "Construction myStruct." << this << endl;
   };

   ~myStruct( )
   {
      cout << "Destructing myStruct." << this << endl;
   };

   void *__CRTDECL operator new(size_t size, size_t realSize)
   {	// allocate the buffer for your required size
	return malloc(realSize);
   }

   void __CRTDECL operator delete(void * ptr, size_t) 
   {	// free the buffer
	free (ptr);
   }
};


int main( ) 
{
   // 1) using our custom new / delete operator
   const int nSize = sizeof(myStruct) + 100;
   myStruct* pStruct1  = new (nSize) myStruct;
   delete pStruct1 ;

   //

   // 2) using the placement new / delete operator
   char preAllocatedBuffer[nSize];  
   myStruct* pStruct2  = ::new( &preAllocatedBuffer[0] ) myStruct;
   <code>pStruct2->~myStruct();</code>
}

myStruct* pStruct2  = ::new myStruct[2];

Rajkumar R wrote:

the placement new

...

::new( &preAllocatedBuffer[0] ) myStruct;

Rajkumar R wrote:

C++ is powerful

Hamed Mosavi wrote:

I wish it had built in support for multi threading.

Rajkumar R wrote:

OS concepts not language specific

int elements=3;
testclass** parray= new testclass* [elements];
for (int i=0;i<elements; i++
{
   parray[i] = testclass::New();
}

tobse wrote:

and deleting with delete [] parray works fine

std::vector<testclass*>vectortestclass;<br />
	<br />
	// Create<br />
	testclass* t=0;<br />
	int elements=5;<br />
	for (int i=0;i<elements;++i)<br />
	{<br />
	        t=testclass::New();<br />
		vectortestclass.push_back(t);<br />
	};

for (int j=0;j<vectortestclass.size();++j)<br />
	{

vectortestclass[j]->Delete();   <br />
};<br />
vectortestclass.clear();