How to Use LINQ Max and Min in C# - Simple Guide

In C#, use Max() and Min() methods from LINQ to find the largest and smallest values in a collection. These methods work on arrays, lists, or any enumerable data and return the maximum or minimum element respectively.

Syntax

The Max() and Min() methods are called on a collection to find the highest or lowest value. You can use them directly on numeric collections or with a selector function for complex types.

• Max: collection.Max() or collection.Max(x => x.Property)
• Min: collection.Min() or collection.Min(x => x.Property)

These methods return the maximum or minimum value found.

csharp

var maxValue = collection.Max();
var minValue = collection.Min();

// With selector
var maxProperty = collection.Max(x => x.Property);
var minProperty = collection.Min(x => x.Property);

Example

This example shows how to find the maximum and minimum numbers in a list using LINQ's Max() and Min() methods.

csharp

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 5, 3, 9, 1, 7 };

        int maxNumber = numbers.Max();
        int minNumber = numbers.Min();

        Console.WriteLine($"Max number: {maxNumber}");
        Console.WriteLine($"Min number: {minNumber}");
    }
}

Output

Max number: 9
Min number: 1

Common Pitfalls

Common mistakes when using Max() and Min() include:

• Calling these methods on an empty collection causes an InvalidOperationException.
• Using them on collections with null values without handling can cause errors.
• For complex objects, forgetting to provide a selector function to specify which property to compare.

Always check if the collection has elements before calling Max() or Min().

csharp

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        List<int> emptyList = new List<int>();

        // Wrong: throws exception
        // int max = emptyList.Max();

        // Right: check before calling
        if (emptyList.Any())
        {
            int max = emptyList.Max();
            Console.WriteLine(max);
        }
        else
        {
            Console.WriteLine("List is empty.");
        }
    }
}

Output

List is empty.

Quick Reference

Method	Description	Example
Max()	Returns the largest value in a collection	numbers.Max()
Min()	Returns the smallest value in a collection	numbers.Min()
Max(selector)	Returns the largest value based on a property	people.Max(p => p.Age)
Min(selector)	Returns the smallest value based on a property	people.Min(p => p.Age)

Key Takeaways

Use LINQ's Max() and Min() to find highest and lowest values in collections easily.

Always check if the collection is not empty before calling Max() or Min() to avoid exceptions.

For complex objects, provide a selector function to specify which property to compare.

Max() and Min() work on any IEnumerable including arrays and lists.

Handle null values carefully to prevent runtime errors.