pointer return by new check in C++

Question

What is the best way to check the pointer return by a new operator I see following type of code. Assume I have class Test

Type 1

Test *ptr = new Test;
if ( ptr == NULL ) {
}

Type 2

Test *ptr = new Test;
if ( !ptr ) {
}

Type 3

Test *ptr = new Test;
if ( ptr == (Test*)0 ) {
}

Answer 1

You do not check new for null it throws an exception std::bad_alloc in case it fails.
So you handle the exception.

Ofcourse, the above rule applies if you are not using the nothrow version of new.

 try
  {
    Test *ptr = new Test;
  }
  catch (std::bad_alloc &e)
  {
    cout << "new Failed";
  }

Answer 2

By default new should throw an bad_alloc exception, so no checks should be necessary.

On the other hand VC6 do return 0 on a bad_alloc in that case Type 3 should be perfectly fine in cases where you do not have nullptr (which is in the C++11 standard)

Another way to be able to test for NULL is to call new with std::nothrow:

ptr = new(std::nothrow) Test();

In any case remember that you do not have to catch every bad_alloc where it is thrown. You are better off catching it where you can respond to it (free memory or die gracefully).