在C#中，可以使用內置的System.Xml.Serialization命名空間和System.Runtime.Serialization.Json命名空間來實現變量的XML和JSON序列化。

首先，我們來看如何實現變量的XML序列化：

using System;
using System.IO;
using System.Xml.Serialization;

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

class Program
{
    static void Main()
    {
        Person person = new Person { Name = "Alice", Age = 30 };

        XmlSerializer xmlSerializer = new XmlSerializer(typeof(Person));
        using (TextWriter writer = new StreamWriter("person.xml"))
        {
            xmlSerializer.Serialize(writer, person);
        }
    }
}

接下來，我們來看如何實現變量的JSON序列化：

using System;
using System.IO;
using System.Runtime.Serialization.Json;

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

class Program
{
    static void Main()
    {
        Person person = new Person { Name = "Alice", Age = 30 };

        DataContractJsonSerializer jsonSerializer = new DataContractJsonSerializer(typeof(Person));
        using (MemoryStream stream = new MemoryStream())
        {
            jsonSerializer.WriteObject(stream, person);
            string json = System.Text.Encoding.UTF8.GetString(stream.ToArray());
            Console.WriteLine(json);
        }
    }
}

以上示例演示了如何將Person對象序列化為XML和JSON格式的數據。可以根據需要對代碼進行調整以滿足特定的序列化需求。