详解C# List<T>的Contains,Exists,Any,Where性能对比
https://zxbcw.cn/post/201932/
新建一个Person类
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public class Person { public Person( string name, int id) { Name = name; Id = id; } public string Name { get ; set ; } public int Id { get ; set ; } } |
初始化List 中有一百万条数据,然后分别通过每种方法判断xiaoming是否在List中,代码如下
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static void Main( string [] args) { List<Person> persons = new List<Person>(); //初始化persons数据 for ( int i = 0; i < 1000000; i++) { Person person = new Person( "My" + i,i); persons.Add(person); } Person xiaoming= new Person( "My999999" , 999999); //下面通过三种方法判断persons中是否包含xiaoming Stopwatch watch = new Stopwatch(); watch.Start(); bool a = persons.Contains(xiaoming); watch.Stop(); Stopwatch watch1 = new Stopwatch(); watch1.Start(); bool b = persons.Exists(x=>x.Id==xiaoming.Id); watch1.Stop(); Stopwatch watch2 = new Stopwatch(); watch2.Start(); bool c = persons.Where(x=>x.Id==xiaoming.Id).Any(); watch2.Stop(); Stopwatch watch3 = new Stopwatch(); watch3.Start(); bool d = persons.Any(x => x.Id == xiaoming.Id); watch3.Stop(); Console.WriteLine( "Contains耗时:" + watch.Elapsed.TotalMilliseconds); Console.WriteLine( "Exists耗时:" + watch1.Elapsed.TotalMilliseconds); Console.WriteLine( "Where耗时:" + watch2.Elapsed.TotalMilliseconds); Console.WriteLine( "Any耗时:" + watch3.Elapsed.TotalMilliseconds); Console.ReadLine(); } |
执行结果如下图所示
结论
通过上图可以看出性能排序为
Contains > Exists > Where > Any
注意:
Contains中不能带查询条件