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c# lambda表达式学习

2021-05-26 Windows程序

public void button1_Click(object sender, EventArgs e) { MessageBox.Show("ok"); } this.button1.Click += button1_Click;

2. 匿名委托:

this.button1.Click += delegate(object sender, EventArgs e) { MessageBox.Show("Click"); };

3. LAMDA表达式:

this.button1.Click += ((sender, e) => { MessageBox.Show("Click"); } );

编译器会自动推算出表达式中的类型。

4. 过滤条件:

List<User> users = new List<User>(); Func<User, bool> predicate = ( (user) => { return user.UserId > 100; } ); List<User> temps = users.Where(predicate).ToList();

等同于:

List<User> temps = users.Where(p => p.UserId > 100).ToList();

List<User> temps = (from p in users where p.UserId > 100 select p).ToList();

List<User> users = new List<User>(); Func<User, bool> predicate = ( (user) => user.UserId > 100 ); List<User> temps = users.Where(predicate).ToList();

单挑语句时不需要使用{},同时可以不使用return来返回结果。

5. 排序:

List<User> users = new List<User>(); List<User> temp1 = users.OrderBy(p=>p.UserId).ToList(); Func<User, int> orderby = (user => user.UserId); List<User> temp2 = users.OrderBy(orderby).ToList();

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