在0xC0000005中的0x6ececafa出现未处理的异常：访问冲突写入位置0x00000000

Question

Getting exception in the following code.

HRESULT GetRemovableDrive(
    __out   LPDWORD   lpdwRemovableDriveCount,
    __out   CHAR*     szRemovableDrive )
{
    INT     iDriveCnt                   = 0;
    CHAR   TempDrive[ MAX_PATH ]       = { TEXT('\0') };

hResult = CheckDriveReady( tzDriveName, &bIsDeviceReady );
                    if ( !hResult && TRUE == bIsDeviceReady )
                    {
                        //
                        // Copy drive name
                        //
                        strcpy_s ( TempDrive, tzDriveName );
                        memcpy(szRemovableDrive + iDriveCnt, TempDrive, 1);
                        iDriveCnt++;
                        ( *lpdwRemovableDriveCount )++;
                    } // if
}

Getting exception while performing the memcpy as unhandled exception :Access violation writing location 0x00000000.

Answer 1

The message is pretty clear. You are writing to address 0 on the call to memcpy() . That means that szRemovableDrive and iDriveCnt are both 0 since that's the write destination address. The caller is likely passing in a NULL pointer to GetRemoveableDrive() for that parameter.