Re: Using malloc in C++
On Jun 28, 5:31 pm, Stuart Golodetz <b...@blah.com> wrote:
On 28/06/2010 12:20, Bharath wrote:
Hi all,
I am trying to use malloc to allocate memory to an object. Something
like:
TestClass *obj = (TestClass *) malloc(sizeof(TestClass));
Its obvious that the constructor doesn't get called in the above case,
nor the destructor when I free it.
Is there a way that I can invoke the constructor after the malloc
statement?
I believe that's what 'new' does isn't it? It allocates memory and
then invokes the constructor.
Thanks,
-Bharath
#include <iostream>
#include <memory>
struct X
{
X() { std::cout << "X()\n"; }
~X() { std::cout << "~X()\n"; }
};
void test_malloc()
{
X *p = static_cast<X*>(malloc(sizeof(X)));
new (p) X;
p->~X();
free(p);
}
void test_operator_new()
{
X *p = static_cast<X*>(::operator new(sizeof(X)));
new (p) X;
p->~X();
::operator delete(p);
}
void test_new()
{
X *p = new X;
delete p;
}
int main()
{
test_malloc();
test_operator_new();
test_new();
return 0;
}
Cheers,
Stu
Wow Stu, that clears up the confusion. I had an idea that I had to use
the new operator to call the constructor again, but wasn't sure how.
Thanks,
-Bharath
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