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question Constructor (and Destructor?) problem

audinue (35)
Anyone know how to invoke constructor in the malloc/realloc-ed classes?

I have this code for reference:
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class Test
{
   int a;

public:
   Test(int a)
   {
      this->a = a;
   };

   int getA()
   {
      return a;
   };
};

#include <cstdlib>
#include <cstdio>

int main()
{
   Test *a = (Test *)malloc(sizeof(Test));

   /*
    * Calling Test's constructor ??
    */

   //printf("%d\n", a->getA()); //forbidden!
};


Thanks in advance.
satm2008 (148)
Not sure if malloc() works like new opeartor in C++ in terms of calling a default constructor. I guess it would call at least a base/default constructor but your code would give you a compiler error as default constructor is missing.
In C++, the new operator can be given to call a parameterized constructor for the class/object being allocated.

Just try adding a default constructor and compile it. I guess it would be OK.

Good luck :)
audinue (35)
Oh my...

I just wonder to make an ObjectPool (with constructors),... using malloc/realloc/free.

But I think it wouldn't be possible in C++, isn't it?

*sob*
hooked (4)
Maybe you can do it like this:
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Test *a = (Test *)malloc(sizeof(Test));
a->Test::Test(0);


but I am not sure if it can work because I am not sure if it is in ISO
helios (9402)
Constructors can't be called directly.
jsmith (5804)
You must use new when instantiating classes. You cannot use malloc.
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