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CallNtPowerInformation (powrprof)
Sets or retrieves power information.

C# Signature:

[DllImport("powrprof.dll", SetLastError=true)]
private static extern UInt32 CallNtPowerInformation(
     Int32 InformationLevel,
     IntPtr lpInputBuffer,
     UInt32 nInputBufferSize,
     IntPtr lpOutputBuffer,
     UInt32 nOutputBufferSize);

[DllImport("powrprof.dll", SetLastError = true)]
private static extern uint CallNtPowerInformation(
     int informationLevel,
     IntPtr lpInputBuffer,
     uint nInputBufferSize,
     IntPtr lpOutputBuffer,
     uint nOutputBufferSize);

VB Signature:

<DllImport("powrprof.dll", SetLastError := True)> _
Private Shared Function CallNtPowerInformation(InformationLevel As Int32, lpInputBuffer As IntPtr, nInputBufferSize As UInt32, lpOutputBuffer As IntPtr, nOutputBufferSize As UInt32) As UInt32

End Function

User-Defined Types:


Alternative Managed API:

Do you know one? Please contribute it!


InformationLevel parameter must be one of the POWER_INFORMATION_LEVEL enumeration type values.

Tips & Tricks:

This is obsolete on Vista. Try GetCurrentPowerPolicies() to get information on both XP and Vista.

Sample Code:

  IntPtr status = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(SYSTEM_BATTERY_STATE)));
  uint retval = CallNtPowerInformation(
    5,  // SystemBatteryState

  SYSTEM_BATTERY_STATE batt_status = (SYSTEM_BATTERY_STATE)Marshal.PtrToStructure(status, typeof(SYSTEM_BATTERY_STATE));

Sample Code:

    class Program
    const int ProcessorInformation = 11;
    const uint STATUS_SUCCESS = 0;

        public uint Number;
        public uint MaxMhz;
        public uint CurrentMhz;
        public uint MhzLimit;
        public uint MaxIdleState;
        public uint CurrentIdleState;

    static extern uint CallNtPowerInformation(
        int InformationLevel,
        IntPtr lpInputBuffer,
        int nInputBufferSize,
        [Out] PROCESSOR_POWER_INFORMATION[] lpOutputBuffer,
        int nOutputBufferSize

    static void Main(string[] args)
        int procCount = Environment.ProcessorCount;
        uint retval = CallNtPowerInformation(
        procInfo.Length * Marshal.SizeOf(typeof(PROCESSOR_POWER_INFORMATION))
        if (retval == STATUS_SUCCESS)
        foreach (var item in procInfo)


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