C# 基本知识纪录

1：获取IP地址

PC有多个网络适配器，例如蓝牙等，这些都是有IP地址的，所以需要获取出来的IP地址可能是多个的，根据自己的需求获取对应的IP地址

 NetworkInterface[] interfaces= NetworkInterface.GetAllNetworkInterfaces();

            foreach (var networkInterface in interfaces)
            {
                UnicastIPAddressInformationCollection addresses = networkInterface.GetIPProperties().UnicastAddresses;
                foreach (var address in addresses)
                {
                    if (address.Address.AddressFamily == AddressFamily.InterNetwork)
                    {
                        Console.WriteLine("IP地址{0}",address.Address.ToString());
                    }
                }
            }

结果：

2：获取网络数据

获取一个网页的源码

 string a= "";
            WebRequest request=WebRequest.Create("https://www.baidu.com");
            using (WebResponse response=request.GetResponse())
            {
                using (StreamReader reader=new StreamReader(response.GetResponseStream()))
                {
                    a=reader.ReadToEnd();
                    Console.WriteLine("html:"+a);
                }
            }

3：对一个数字保留两位有效数字

 decimal value = 4325345345.34534534653464M;
            Console.WriteLine(value.ToString());
            Console.WriteLine(value.ToString("#.##"));
            Console.WriteLine(String.Format("{0:0.00}",value));
            Console.WriteLine(value.ToString("n2"));

结果：

4：删除数组中重复项

   string[] array=new string[] {"1","1","2","2"};
            string[] newarray=array.Distinct().ToArray();
 
  
5：对字典中的值排序，使用LINQ
 
  
 Dictionary directory = new Dictionary();
            directory.Add("1","one");
            directory.Add("5", "five");
            directory.Add("2", "two");
            directory.Add("4", "four");
            List> keyValuePairs = directory.ToList();
            var sort = from entry in directory orderby entry.Value ascending select entry;
            foreach (KeyValuePair pair in sort)
            {
                Console.WriteLine(pair.Key+","+pair.Value);
            }