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Quantifier operations in LINQ (C#)

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Quantifier operations return a Boolean value that indicates whether some or all of the elements in a sequence satisfy a condition.

The following illustration depicts two different quantifier operations on two different source sequences. The first operation asks if any of the elements are the character 'A'. The second operation asks if all the elements are the character 'A'. Both methods return true in this example.

LINQ Quantifier Operations

Method Name Description C# Query Expression Syntax More Information
All Determines whether all the elements in a sequence satisfy a condition. Not applicable. Enumerable.All
Queryable.All
Any Determines whether any elements in a sequence satisfy a condition. Not applicable. Enumerable.Any
Queryable.Any
Contains Determines whether a sequence contains a specified element. Not applicable. Enumerable.Contains
Queryable.Contains

All

The following example uses the All to find students that scored above 70 on all exams.

IEnumerable<string> names = from student in students
                            where student.Scores.All(score => score > 70)
                            select $"{student.FirstName} {student.LastName}: {string.Join(", ", student.Scores.Select(s => s.ToString()))}";

foreach (string name in names)
{
    Console.WriteLine($"{name}");
}

// This code produces the following output:
//
// Cesar Garcia: 71, 86, 77, 97
// Nancy Engström: 75, 73, 78, 83
// Ifunanya Ugomma: 84, 82, 96, 80

Any

The following example uses the Any to find students that scored greater than 95 on any exam.

IEnumerable<string> names = from student in students
                            where student.Scores.Any(score => score > 95)
                            select $"{student.FirstName} {student.LastName}: {student.Scores.Max()}";

foreach (string name in names)
{
    Console.WriteLine($"{name}");
}

// This code produces the following output:
//
// Svetlana Omelchenko: 97
// Cesar Garcia: 97
// Debra Garcia: 96
// Ifeanacho Jamuike: 98
// Ifunanya Ugomma: 96
// Michelle Caruana: 97
// Nwanneka Ifeoma: 98
// Martina Mattsson: 96
// Anastasiya Sazonova: 96
// Jesper Jakobsson: 98
// Max Lindgren: 96

Contains

The following example uses the Contains to find students that scored exactly 95 on an exam.

IEnumerable<string> names = from student in students
                            where student.Scores.Contains(95)
                            select $"{student.FirstName} {student.LastName}: {string.Join(", ", student.Scores.Select(s => s.ToString()))}";

foreach (string name in names)
{
    Console.WriteLine($"{name}");
}

// This code produces the following output:
//
// Claire O'Donnell: 56, 78, 95, 95
// Donald Urquhart: 92, 90, 95, 57

See also