letting new operator return NULL;

[angrybeaver]

Hi Folks...

how can I make the new-operator return null, if something fatal in the constructor happens?

Greets
Seb

[dude_1967]

beaver,

I do not fully understand the question. Perhaps the nothrow version of the operator new would be useful.

Sincerely, Chris.



#include <iostream>
#include <memory>

class c
{
private:

unsigned char* pb;
int some_member;

public:

c()
{
// Returns 0 if allocation fails.
pb = new (::std::nothrow) unsigned char[1024 * 1024];

if(!pb)
{
return;
}

some_member = 0;
}

~c()
{
if(pb)
{
delete [] pb;
}
}

public:

const bool valid(void) const { return pb != NULL; }

};

int main(int argc, char* argv[])
{
c C;

::std::cout << (C.valid() ? 1 : 0) << ::std::endl;

return 1;
}

[Rabelo]

Returning null from an allocator is an old C style. C++ was designed to work with exeptions. On this case you use CMemoryExeption, for example:

...
try
{
CString MyString = new CString;
}
catch(CMemoryException* e)
{
deal with the error here, you can see the structure e to pick the exact reason of the error
}
....

[kakalake]

Override the new Operator

inline void* operator new( unsigned int size )
{
return NULL;
}


cu