如何在程序中调系统音量？

Question

要用到什么函数？
要求一启动程序，就要把系统音量调到中间
要用到API的什么函数？
谢谢:)

Answer 1

为什么没人回答？？？
up,up

Answer 2

给焦急等待的人的福音，两个函数一看就明白了：
(要include "mmsystem.h"和link "winmm.lib")void CVolumeDlg::SetVolume( const DWORD dwVolume )
{
    MMRESULT                        result;
    HMIXER                          hMixer;
    MIXERLINE                       ml   = {0};
    MIXERLINECONTROLS               mlc  = {0};
    MIXERCONTROL                    mc   = {0};
    MIXERCONTROLDETAILS             mcd  = {0};
    MIXERCONTROLDETAILS_UNSIGNED    mcdu = {0};
    // get a handle to the mixer device
    result = mixerOpen(&hMixer, MIXER_OBJECTF_MIXER, 0, 0, 0);
    if (MMSYSERR_NOERROR == result)
    {
        ml.cbStruct        = sizeof(MIXERLINE);
        ml.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;        // get the speaker line of the mixer device
        result = mixerGetLineInfo((HMIXEROBJ) hMixer, &ml, MIXER_GETLINEINFOF_COMPONENTTYPE);
        if (MMSYSERR_NOERROR == result)
        {
            mlc.cbStruct      = sizeof(MIXERLINECONTROLS);
            mlc.dwLineID      = ml.dwLineID;
            mlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
            mlc.cControls     = 1;
            mlc.pamxctrl      = &mc;
            mlc.cbmxctrl      = sizeof(MIXERCONTROL);            // get the volume controls associated with the speaker line
            result = mixerGetLineControls((HMIXEROBJ) hMixer, &mlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
            if (MMSYSERR_NOERROR == result)
            {
                mcdu.dwValue    = dwVolume;                mcd.cbStruct    = sizeof(MIXERCONTROLDETAILS);
                mcd.hwndOwner   = 0;
                mcd.dwControlID = mc.dwControlID;
                mcd.paDetails   = &mcdu;
                mcd.cbDetails   = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
                mcd.cChannels   = 1;                // set the volume
                result = mixerSetControlDetails((HMIXEROBJ) hMixer, &mcd, MIXER_SETCONTROLDETAILSF_VALUE);
                if (MMSYSERR_NOERROR == result)
                    AfxMessageBox("Volume changed!");
                else
                    AfxMessageBox("mixerSetControlDetails() failed");
            }
            else
                AfxMessageBox("mixerGetLineControls() failed");
        }
        else
            AfxMessageBox("mixerGetLineInfo() failed");
    
        mixerClose(hMixer);
    }
    else
        AfxMessageBox("mixerOpen() failed");
}//====================================================================DWORD CVolumeDlg::GetVolume( void )
{
    DWORD                           dwVolume = -1;
    MMRESULT                        result;
    HMIXER                          hMixer;
    MIXERLINE                       ml   = {0};
    MIXERLINECONTROLS               mlc  = {0};
    MIXERCONTROL                    mc   = {0};
    MIXERCONTROLDETAILS             mcd  = {0};
    MIXERCONTROLDETAILS_UNSIGNED    mcdu = {0};
    // get a handle to the mixer device
    result = mixerOpen(&hMixer, 0, 0, 0, MIXER_OBJECTF_HMIXER);
    if (MMSYSERR_NOERROR == result)
    {
        ml.cbStruct        = sizeof(MIXERLINE);
        ml.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;        // get the speaker line of the mixer device
        result = mixerGetLineInfo((HMIXEROBJ) hMixer, &ml, MIXER_GETLINEINFOF_COMPONENTTYPE);
        if (MMSYSERR_NOERROR == result)
        {
            mlc.cbStruct      = sizeof(MIXERLINECONTROLS);
            mlc.dwLineID      = ml.dwLineID;
            mlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
            mlc.cControls     = 1;
            mlc.pamxctrl      = &mc;
            mlc.cbmxctrl      = sizeof(MIXERCONTROL);            // get the volume controls associated with the speaker line
            result = mixerGetLineControls((HMIXEROBJ) hMixer, &mlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
            if (MMSYSERR_NOERROR == result)
            {
                mcd.cbStruct    = sizeof(MIXERCONTROLDETAILS);
                mcd.hwndOwner   = 0;
                mcd.dwControlID = mc.dwControlID;
                mcd.paDetails   = &mcdu;
                mcd.cbDetails   = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
                mcd.cChannels   = 1;                // get the volume
                result = mixerGetControlDetails((HMIXEROBJ) hMixer, &mcd, MIXER_SETCONTROLDETAILSF_VALUE);
                if (MMSYSERR_NOERROR == result)
                    dwVolume = mcdu.dwValue;
                else
                    AfxMessageBox("mixerGetControlDetails() failed");
            }
            else
                AfxMessageBox("mixerGetLineControls() failed");
        }
        else
            AfxMessageBox("mixerGetLineInfo() failed");
    
        mixerClose(hMixer);
    }
    else
        AfxMessageBox("mixerOpen() failed");    return (dwVolume);
}