// C++  XPCOM

NS_IMETHODIMP MyComponent::GetArray(PRUint32* count, PRInt32** retv) {

    *count = 10;

    *retv = (PRInt32*)nsMemory::Alloc(*count * sizeof(PRInt32));

    for (int i = 0; i < 10; ++i) (*retv)[i] = i;

    return NS_OK;

}

Line 3: error: 'NS_IMETHODIMP' does not name a type
compilation terminated due to -Wfatal-errors.