memory allocation operator new / delete, new [] / delete[]
Hello
I made a simple code.
Please analyse it and make debug !
My question is:
Why 16 bytes is allocated for 3 MyClass1 objects ??
sizeof(MyClass1) = 4
So for 3 objects need 12 bytes.
When I made debug I saw a_bytes = 16 in function
operator new[] ( size_t a_bytes ) !!!
WHY ?
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|
struct CAlloc
{
static void* operator new ( size_t a_bytes )
{
void *storage = malloc( a_bytes );
if ( NULL == storage )
throw "allocation fail : no free memory";
return storage;
}
static void operator delete ( void* a_ptr )
{
free( a_ptr );
}
static void* operator new[] ( size_t a_bytes )
{
void *storage = malloc( a_bytes );
if ( NULL == storage )
throw "allocation fail : no free memory";
return storage;
}
static void operator delete[] ( void* a_ptr )
{
free( a_ptr );
}
};
//-----------------------------------
class MyClass1 : public CAlloc
{
public:
MyClass1()
{
m_Data = 0;
}
~MyClass1()
{
}
private:
int m_Data;
};
//-----------------------------------
int main ()
{
// 4 bytes !!! correct !!!
int size = sizeof(MyClass1);
// case1 1
// alloc 4 bytes ; correct !!!
MyClass1* pObj1 = new MyClass1;
delete pObj1;
// case 2
// I want to alloc memory for 3 objects 3 * 4 = 12 bytes !
// but a_bytes is 16 bytes ????
MyClass1* pObj2 = new MyClass1[3];
delete [] pObj2;
return 0;
}
|
In line 68, delete [] pObj2;, how does the program know how many elements are to be destroyed?
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