Question

Im having issues on the following code when converting to Int64 or any big number. Any help is appreciated.

public static void GetDiskspace(string MachineName, string DriveLetter) 
{ 
  ConnectionOptions options = new ConnectionOptions(); 
  ManagementScope scope = new ManagementScope("\\\\" + MachineName + "\\root\\cimv2",  
  options); 
  scope.Connect(); 
  SelectQuery query1 = new SelectQuery("Select * from Win32_LogicalDisk"); 

  ManagementObjectSearcher searcher1 = new ManagementObjectSearcher(scope, query1); 
  ManagementObjectCollection queryCollection1 = searcher1.Get(); 

  foreach (ManagementObject mo in queryCollection1) 
  { 
      // Display Logical Disks information 

      if (mo["Name"].Equals(DriveLetter.ToUpper()+":"))
          if (((Int64)mo["FreeSpace"]) < (1024 * 1024 * 100)) //100GB  <<----HERE IS WHERE I GET THE ERROR
          {
              Console.WriteLine(MachineName + " ALERT. LOW SPACE ON DRIVE " + mo["Name"]);
              Console.WriteLine();
              Console.WriteLine("              Disk Name : {0}", mo["Name"]);
              Console.WriteLine("              Disk Size : {0}", mo["Size"]);
              Console.WriteLine("              FreeSpace : {0}", mo["FreeSpace"]);
              Console.WriteLine("          Disk DeviceID : {0}", mo["DeviceID"]);
              Console.WriteLine("        Disk VolumeName : {0}", mo["VolumeName"]);
              Console.WriteLine("        Disk SystemName : {0}", mo["SystemName"]);
              Console.WriteLine("Disk VolumeSerialNumber : {0}", mo["VolumeSerialNumber"]);
              Console.WriteLine();
          }
  } 
  string line; 
  line = Console.ReadLine();  
} 

EDIT: changed “Size” to “FreeSpace”.

Answer 1

It’s ulong boxed into object. So you can only unbox it to ulong (i.e. UInt64).

 if (((UInt64)mo["Size"]) < (1024 * 1024 * 100))

Have a look at Win32_LogicalDisk class

class Win32_LogicalDisk : CIM_LogicalDisk
{
    ...
    uint64   Size;
    ...
};

An extract from Win32_LogicalDisk class properties description:

Size

Data type: uint64 
Access type: Read-only Size of the disk drive.
This property is inherited from CIM_LogicalDisk.

P.S.:

1) Actually if you do need to have Int64, you can do the following cast:

(Int64)(UInt64)mo["Size"]

2) You could read this article by Eric Lippert, clarifying the essence of the exception in question.