Calling API functions using C#

//Created By Ajit Mungale
namespace UsingAPI
{

	using System;
    using System.Drawing;
    using System.Collections;
    using System.ComponentModel;
    using System.WinForms;
    using System.Data;
	using System.Runtime.InteropServices; 

	//Struct to retrive system info
	[StructLayout(LayoutKind.Sequential)]   
	public struct SYSTEM_INFO {
			public  uint  dwOemId;
			public  uint  dwPageSize;
			public  uint  lpMinimumApplicationAddress;
			public	uint  lpMaximumApplicationAddress;
			public  uint  dwActiveProcessorMask;
			public  uint  dwNumberOfProcessors;
			public  uint  dwProcessorType;
			public  uint  dwAllocationGranularity;
			public  uint  dwProcessorLevel;
			public  uint  dwProcessorRevision;		
		}
	//struct to retrive memory status
	[StructLayout(LayoutKind.Sequential)]   
	public struct MEMORYSTATUS
	{
	        public  uint dwLength;
			public  uint dwMemoryLoad;
			public  uint dwTotalPhys;
			public  uint dwAvailPhys;
			public  uint dwTotalPageFile;
			public  uint dwAvailPageFile;
			public  uint dwTotalVirtual;
			public  uint dwAvailVirtual;
	 }

 
    public class Form1 : System.WinForms.Form
    {
	
        private System.ComponentModel.Container components;
		private System.WinForms.MenuItem menuAbout;
		private System.WinForms.MainMenu mainMenu1;
		private System.WinForms.ListBox listBox1;
		private System.WinForms.Button button1;
		
		
		//To get system information
		[DllImport("kernel32")]
		static extern void GetSystemInfo(ref SYSTEM_INFO pSI);
		
		//To get Memory status
		[DllImport("kernel32")]
		static extern void GlobalMemoryStatus(ref MEMORYSTATUS buf);
		
      
		//Cnstants used for processor types
		public const int PROCESSOR_INTEL_386 = 386;
		public const int PROCESSOR_INTEL_486 = 486;
		public const int PROCESSOR_INTEL_PENTIUM = 586;
		public const int PROCESSOR_MIPS_R4000 = 4000;
		public const int PROCESSOR_ALPHA_21064 = 21064;
        
		public Form1()
        {
            InitializeComponent();
        }

        public override void Dispose()
        {
            base.Dispose();
            components.Dispose();
        }

        private void InitializeComponent()
		{
			this.components = new System.ComponentModel.Container ();
			this.mainMenu1 = new System.WinForms.MainMenu ();
			this.button1 = new System.WinForms.Button ();
			this.listBox1 = new System.WinForms.ListBox ();
			this.menuAbout = new System.WinForms.MenuItem ();
			//@this.TrayHeight = 90;
			//@this.TrayLargeIcon = false;
			//@this.TrayAutoArrange = true;
			//@mainMenu1.SetLocation (new System.Drawing.Point (7, 7));
			mainMenu1.MenuItems.All = new System.WinForms.MenuItem[1] {this.menuAbout};
			button1.Location = new System.Drawing.Point (148, 168);
			button1.Size = new System.Drawing.Size (112, 32);
			button1.TabIndex = 0;
			button1.Text = "&Get Info";
			button1.Click += new System.EventHandler (this.button1_Click);
			listBox1.Location = new System.Drawing.Point (20, 8);
			listBox1.Size = new System.Drawing.Size (368, 147);
			listBox1.TabIndex = 1;
			menuAbout.Text = "&About";
			menuAbout.Index = 0;
			menuAbout.Click += new System.EventHandler (this.menuAbout_Click);
			this.Text = "System Information - Using API";
			this.MaximizeBox = false;
			this.AutoScaleBaseSize = new System.Drawing.Size (5, 13);
			this.MinimizeBox = false;
			this.Menu = this.mainMenu1;
			this.ClientSize = new System.Drawing.Size (408, 213);
			this.Controls.Add (this.listBox1);
			this.Controls.Add (this.button1);
		}

		protected void menuAbout_Click (object sender, System.EventArgs e)
		{
			Form abt=new about() ;
			abt.ShowDialog(); 
		}
		
		protected void button1_Click (object sender, System.EventArgs e)
		{
			
			try
			{
				SYSTEM_INFO pSI = new SYSTEM_INFO();
				GetSystemInfo(ref pSI);
				string CPUType;
				switch (pSI.dwProcessorType)
				{
									
					case PROCESSOR_INTEL_386	:
						 CPUType= "Intel 386";
						 break;
					case PROCESSOR_INTEL_486	:
						CPUType = "Intel 486" ;
						break;
					case PROCESSOR_INTEL_PENTIUM	:
						CPUType =  "Intel Pentium";
						break;
					case PROCESSOR_MIPS_R4000	:
						 CPUType =  "MIPS R4000";
						 break;
					case PROCESSOR_ALPHA_21064	:
						CPUType =  "DEC Alpha 21064";
						break;
					default :
						 CPUType = "(unknown)";
				}
				
				listBox1.InsertItem (0,"Active Processor Mask :		" + pSI.dwActiveProcessorMask.ToString());
				listBox1.InsertItem (1,"Allocation Granularity :		" + pSI.dwAllocationGranularity.ToString()); 				
				listBox1.InsertItem (2,"Number Of Processors :		" + pSI.dwNumberOfProcessors.ToString());
				listBox1.InsertItem (3,"OEM ID :				" + pSI.dwOemId.ToString());
				listBox1.InsertItem (4,"Page Size :			" + pSI.dwPageSize.ToString());
				// Processor Level (Req filtering to get level)
				listBox1.InsertItem (5,"Processor Level Value :		" + pSI.dwProcessorLevel.ToString());
				listBox1.InsertItem (6,"Processor Revision :		" + pSI.dwProcessorRevision.ToString());
				listBox1.InsertItem (7,"CPU type :			" + CPUType); 
				listBox1.InsertItem (8,"Maximum Application Address :	" + pSI.lpMaximumApplicationAddress.ToString());
				listBox1.InsertItem (9,"Minimum Application Address :	" + pSI.lpMinimumApplicationAddress.ToString());
				
			/**************	To retrive info from GlobalMemoryStatus ****************/
				
				MEMORYSTATUS memSt = new MEMORYSTATUS ();				
				GlobalMemoryStatus (ref memSt);
				 
				listBox1.InsertItem(10,"Available Page File :		" + (memSt.dwAvailPageFile/1024).ToString ());
				listBox1.InsertItem(11,"Available Physical Memory :		" + (memSt.dwAvailPhys/1024).ToString()); 				
				listBox1.InsertItem(12,"Available Virtual Memory :		" + (memSt.dwAvailVirtual/1024).ToString ());
				listBox1.InsertItem(13,"Size of structur :			" + memSt.dwLength.ToString()); 
				listBox1.InsertItem(14,"Memory In Use :			" + memSt.dwMemoryLoad.ToString()); 
				listBox1.InsertItem(15,"Total Page Size :			" + (memSt.dwTotalPageFile/1024).ToString ());
				listBox1.InsertItem(16,"Total Physical Memory :		" + (memSt.dwTotalPhys/1024).ToString()); 
				listBox1.InsertItem(17,"Total Virtual Memory :		" + (memSt.dwTotalVirtual/1024).ToString ());
				
			}
			catch(Exception er)
			{
				MessageBox.Show (er.Message); 
			}
		}
        public static void Main(string[] args) 
        {
            try
			{
				Application.Run(new Form1());
			}
			catch(Exception er)
			{
				MessageBox.Show (er.Message ); 
			}

        }
    }
}