the “new” operator in c++, pointer question

Question

Dumb question, but whenever you call new, do you always have a pointer?

SomeClass *person = new SomeClass();

And is that because you need a poi

Answer 1

Yes. If you are asking why it doesn't return a reference instead, since references are nicer than pointers, the answer is historical heritage.

When C++ was in development, if the machine was unable to get memory for the object, a special pointer NULL was returned. This is how it is done in C:

SomeClass *person;
person = (SomeClass*) malloc( sizeof( SomeClass ) );
if ( person == NULL ) fprintf( stderr, "no more people allowed!" );

In standard C++, errors are returned by exception instead:

try {
    SomeClass *person = new SomeClass;
    // do something
} catch ( std::bad_alloc ) {
    std::cerr << "no more people!" << std::endl;
} catch ( ... ) {
    // using exceptions allows for other errors
    // from inside SomeClass::SomeClass too
}

You can still do it the old-fashioned way, though, with nothrow:

SomeClass *person = new( std::nothrow ) SomeClass;
if ( person == NULL ) std::cerr << "no more people allowed!" << std::endl;

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The upshot is, this is perfectly reasonable and good style:

SomeClass &person = * new SomeClass; // don't need no stinkin pointers!