代码功能：使用C#代码获取局域网内有响应的ip地址列表。
代码实现原理：通过调用cmd.exe窗口，使用ping代码，并用arp -a命令，这种方式比开多线程去循环扫描的方式来的简单而有效。
代码如下：
public static ArrayList GetAllLocalIP()
{
Process p = new Process();
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.CreateNoWindow = true;
p.Start();
p.StandardInput.WriteLine("arp -a");
p.StandardInput.WriteLine("exit");
ArrayList list = new ArrayList();
StreamReader reader = p.StandardOutput;
string IPHead = Dns.GetHostByName(Dns.GetHostName()).AddressList[0].ToString().Substring(0, 3);
for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
{
line = line.Trim();
if (line.StartsWith(IPHead) && (line.IndexOf("dynamic") != -1))
{
string IP = line.Substring(0, 15).Trim();
string Mac = line.Substring(line.IndexOf("-") - 2, 0x11).Trim();
LocalMachine localMachine = new LocalMachine();
localMachine.MachineIP = IP;
localMachine.MachineMAC = Mac;
localMachine.MachineName = "";
list.Add(localMachine);
}
}
return list;
}