IGameInputDevice::GetControllerButtonLabels

uint32_t GetControllerButtonLabels(
    uint32_t labelArrayCount,
    GameInputLabel* labelArray
);

uint32_t buttonCount = device->GetControllerButtonCount();
std::vector<GameInputLabel> buttonLabels(buttonCount);
buttonLabels.resize(device->GetControllerButtonLabels(buttonCount, buttonLabels.data()));

std::unique_ptr<bool[]> buttonStates(new bool[buttonCount]);
uint32_t stateCount = reading->GetControllerButtonState(buttonCount, buttonStates.get());

for (uint32_t i = 0; i < buttonLabels.size() && i < stateCount; ++i)
{
    // buttonLabels[i] is the label of the button whose state is buttonStates[i].
}