Summary: in this tutorial, you’ll learn how to use the LINQ All()
method to determine if all elements of a sequence satisfy a specified condition.
Introduction to the LINQ All() method
The All()
is an extension method in LINQ that returns true
if all elements of a sequence satisfy a specified condition. Otherwise, it returns false
.
bool ALL<TSource> (
this IEnumerable<TSource> source,
Func<TSource,bool> predicate
);
Code language: C# (cs)
In this syntax:
source
is an input sequence with the typeIEnumerable<T>
.predicate
is a function that returns true if the element satisfies a condition.
LINQ All() examples
Let’s take some examples of using the All()
extension method.
1) Using LINQ All() method to check if all elements of a sequence satisfy a condition
The following example demonstrates how to use the LINQ All()
method to check if all elements of a sequence satisfy a condition:
using static System.Console;
int[] numbers = { 2, 4, 6, 8 };
bool allEvenNumbers = numbers.All(n => n % 2 == 0 ? true : false);
if (allEvenNumbers)
{
WriteLine("All numbers are even.");
}
Code language: C# (cs)
In this example, the lambda expression n => n % 2 == 0 ? true : false
tests all numbers in the numbers array and returns true if all of them are even.
2) Using LINQ All() method with a sequence of objects
The following program demonstrates how to use the All()
method to check if all employees have a salary greater than 40K:
using static System.Console;
namespace LINQDemo
{
class Employee
{
public string? Name { get; set; }
public string? Department { get; set; }
public int Salary { get; set; }
}
class Program
{
public static void Main()
{
var employees = new List<Employee>() {
new() { Name = "John", Department = "HR", Salary = 50000 },
new() { Name = "Jane", Department = "IT", Salary = 60000 },
new() { Name = "Bob", Department = "HR", Salary = 45000 },
new() { Name = "Sara", Department = "IT", Salary = 55000 },
new() { Name = "Tom", Department = "IT", Salary = 65000 }
};
var result = employees.All(e => e.Salary > 40000);
if (result)
{
WriteLine("All employees have salary greater than 40000");
}
}
}
}
Code language: C# (cs)
Output:
All employees have salary greater than 40000
Code language: plaintext (plaintext)
In this example, the lambda expression e => e.Salary > 40000
applies to each Employee
object and returns true
if all employees have a salary greater than 40000
.
Summary
- Use LINQ
All()
method to determine if all elements in a sequence satisfy a specified condition.