Change Master Volume in Visual C++

To change volume in Vista and Windows 7, use this code:

#include <mmdeviceapi.h>
#include <endpointvolume.h>

bool ChangeVolume(double nVolume,bool bScalar)
{
 
    HRESULT hr=NULL;
    bool decibels = false;
    bool scalar = false;
    double newVolume=nVolume;
 
    CoInitialize(NULL);
    IMMDeviceEnumerator *deviceEnumerator = NULL;
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER, 
                          __uuidof(IMMDeviceEnumerator), (LPVOID *)&deviceEnumerator);
    IMMDevice *defaultDevice = NULL;
 
    hr = deviceEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &defaultDevice);
    deviceEnumerator->Release();
    deviceEnumerator = NULL;
 
    IAudioEndpointVolume *endpointVolume = NULL;
    hr = defaultDevice->Activate(__uuidof(IAudioEndpointVolume), 
         CLSCTX_INPROC_SERVER, NULL, (LPVOID *)&endpointVolume);
    defaultDevice->Release();
    defaultDevice = NULL;
 
    // -------------------------
    float currentVolume = 0;
    endpointVolume->GetMasterVolumeLevel(&currentVolume);
    //printf("Current volume in dB is: %f\n", currentVolume);

    hr = endpointVolume->GetMasterVolumeLevelScalar(&currentVolume);
    //CString strCur=L"";
    //strCur.Format(L"%f",currentVolume);
    //AfxMessageBox(strCur);

    // printf("Current volume as a scalar is: %f\n", currentVolume);
    if (bScalar==false)
    {
        hr = endpointVolume->SetMasterVolumeLevel((float)newVolume, NULL);
    }
    else if (bScalar==true)
    {
        hr = endpointVolume->SetMasterVolumeLevelScalar((float)newVolume, NULL);
    }
    endpointVolume->Release();
 
    CoUninitialize();
 
    return FALSE;
}

The nVolume parameter must be between 0.0 and 1.0.

0.0 means mute and 1.0 means 100.