Aggregation Operator: Max

The Max operator returns the largest numeric element from a collection.

The following example demonstrates Max() on primitive collection.

Example: Max method - C#

IList<int> intList = new List<int>() { 10, 21, 30, 45, 50, 87 };

var largest = intList.Max();

Console.WriteLine("Largest Element: {0}", largest);

var largestEvenElements = intList.Max(i => {
			                        if(i%2 == 0)
				                        return i;
			
			                        return 0;
		                        });

Console.WriteLine("Largest Even Element: {0}", largestEvenElements );

Output:
Largest Element: 87
Largest Even Element: 50

The following example demonstrates Max() method on the complex type collection.

Example: Max operator in method syntax C#

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);
       
Example: Max operator in method syntax VB.Net

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("Oldest Student Age: {0}", oldest)

Output:
Oldest Student Ag: 21

Max returns a result of any data type. The following example shows how you can find a student with the longest name in the collection:

C#: LINQ Max()

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)
    {
        // Student collection
        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)
    }
}
Output:
Student ID: 5, Student Name: Steve
Note : You can use Min extension method/operator the same way as Max.

As per the above example, to find the student with the longest name, you need to implement IComparable<T> interface and compare student names' length in CompareTo method. So now, you can use Max() method which will use CompareTo method in order to return appropriate result.

Max operator in Query Syntax:

Max operator is Not Supported in C# Query syntax. However, it is supported in VB.Net query syntax as shown below.

Example: Max operator in query syntax VB.Net

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("Maximum Age of Student: {0}", maxAge);

Output:
Maximum Age of Student: 21

Learn about another aggregate operator - Sum in the next section.