IAudioEndpointVolume没有名为GetMasterVolumeLevelScalar的成员
IAudioEndpointVolume has no member named GetMasterVolumeLevelScalar
考虑这个程序:
#include <stdio.h>
#include <windows.h>
#include <mmdeviceapi.h>
#include <endpointvolume.h>
#include <math.h>
int main() {
IAudioEndpointVolume *wh;
IMMDevice *ya;
IMMDeviceEnumerator *xr;
CoInitialize(0);
CoCreateInstance(__uuidof(MMDeviceEnumerator), 0, CLSCTX_INPROC_SERVER,
__uuidof(IMMDeviceEnumerator), (void**)&xr);
xr->GetDefaultAudioEndpoint(eRender, eConsole, &ya);
ya->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_ALL, 0, (void**)&wh);
float zu;
wh->GetMasterVolumeLevelScalar(&zu);
printf("%dn", (int) round(100 * zu));
}
我可以把它编译成C++而没有问题:
x86_64-w64-mingw32-g++ vol.cpp -lole32
然而,如果我试图将其编译为C:
x86_64-w64-mingw32-gcc vol.c -lole32
我收到错误,例如:
error: ‘IAudioEndpointVolume’ has no member named ‘GetMasterVolumeLevelScalar’
这个程序似乎不是特别"C++",那么是什么导致了问题另外,我可以更改一些内容,使其编译为C吗?
这似乎做到了:
#include <stdio.h>
#include <initguid.h>
#include <mmdeviceapi.h>
#include <endpointvolume.h>
#include <math.h>
int main() {
IAudioEndpointVolume *wh;
IMMDevice *ya;
IMMDeviceEnumerator *xr;
CoInitialize(0);
CoCreateInstance(&CLSID_MMDeviceEnumerator, 0, CLSCTX_INPROC_SERVER,
&IID_IMMDeviceEnumerator, (void**)&xr);
xr->lpVtbl->GetDefaultAudioEndpoint(xr, eRender, eConsole, &ya);
ya->lpVtbl->Activate(ya, &IID_IAudioEndpointVolume, CLSCTX_ALL,
0, (void**)&wh);
float zu;
wh->lpVtbl->GetMasterVolumeLevelScalar(wh, &zu);
printf("%dn", (int) round(100 * zu));
}
更改:
#include <initguid.h>
&CLSID_MMDeviceEnumerator
而不是__uuidof(MMDeviceEnumerator)
lpVtbl->GetDefaultAudioEndpoint
而不是GetDefaultAudioEndpoint
源
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