Max()方法返回集合中最大的数值元素。
下面的示例演示原始集合上的Max()方法。
IList<int> intList = new List<int>() { 10, 21, 30, 45, 50, 87 }; var largest = intList.Max(); Console.WriteLine("最大元素: {0}", largest); var largestEvenElements = intList.Max(i => { if(i%2 == 0) return i; return 0; }); Console.WriteLine("最大偶数: {0}", largestEvenElements );
最大元素:87 最大偶数:50
下面的示例演示复杂类型集合上的Max()方法。
IList<Student> studentList = new List<Student>>() { new Student() { StudentID = 1, StudentName = "John", Age = 13} , new Student() { StudentID = 2, StudentName = "Moin", Age = 21 } , new Student() { StudentID = 3, StudentName = "Bill", Age = 18 } , new Student() { StudentID = 4, StudentName = "Ram" , Age = 20} , new Student() { StudentID = 5, StudentName = "Ron" , Age = 15 } }; var oldest = studentList.Max(s => s.Age); Console.WriteLine("Oldest Student Age: {0}", oldest);
Dim studentList = New List(Of Student) From { New Student() With {.StudentID = 1, .StudentName = "John", .Age = 13}, New Student() With {.StudentID = 2, .StudentName = "Moin", .Age = 21}, New Student() With {.StudentID = 3, .StudentName = "Bill", .Age = 18}, New Student() With {.StudentID = 4, .StudentName = "Ram", .Age = 20}, New Student() With {.StudentID = 5, .StudentName = "Ron", .Age = 15} } Dim oldest = studentList.Max(Function(s) s.Age) Console.WriteLine("最大的学生年龄: {0}", oldest)
最大的学生年龄:21
Max返回任何数据类型的结果。以下示例显示了如何找到集合中 名称最长 的学生:
public class Student : IComparable<Student> { public int StudentID { get; set; } public string StudentName { get; set; } public int Age { get; set; } public int StandardID { get; set; } public int CompareTo(Student other) { if (this.StudentName.Length >= other.StudentName.Length) return 1; return 0; } } class Program { static void Main(string[] args) { // 学生集合 IList<Student> studentList = new List<Student>>() { new Student() { StudentID = 1, StudentName = "John", Age = 13} , new Student() { StudentID = 2, StudentName = "Moin", Age = 21 } , new Student() { StudentID = 3, StudentName = "Bill", Age = 18 } , new Student() { StudentID = 4, StudentName = "Ram" , Age = 20} , new Student() { StudentID = 5, StudentName = "Steve" , Age = 15 } }; var studentWithLongName = studentList.Max(); Console.WriteLine("Student ID: {0}, Student Name: {1}", .StudentID, studentWithLongName.StudentName) } }
Student ID:5,StudentName :Steve
您可以使用与Max相同的方式使用Min扩展方法/运算符。
根据上面的实例,要找到名字最长的学生,需要实现IComparable<T>接口,并在CompareTo方法中比较学生名字的长度。现在,您可以使用Max()方法,它将使用CompareTo方法来返回适当的结果。
C#查询语法不支持Max运算符。但是,它在VB.Net版查询语法如下所示。
Dim studentList = New List(Of Student) From { New Student() With {.StudentID = 1, .StudentName = "John", .Age = 13}, New Student() With {.StudentID = 2, .StudentName = "Moin", .Age = 21}, New Student() With {.StudentID = 3, .StudentName = "Bill", .Age = 18}, New Student() With {.StudentID = 4, .StudentName = "Ram", .Age = 20}, New Student() With {.StudentID = 5, .StudentName = "Ron", .Age = 15} } Dim maxAge = Aggregate st In studentList Into Max(st.Age) Console.WriteLine("最大学生年龄: {0}", maxAge);
最大学生年龄:21
在下一部分中了解另一个聚合运算符-Sum。