System.Linq
Class Enumerable
Method All
public static bool All<TSource>(
this IEnumerable<TSource> source,
Func<TSource, bool> predicate
)
Summary
Determines whether all elements of a sequence satisfy a condition.
Type Parameters
TSource- The type of the elements of
source.
Returns
true if all elements of the sequence satisfy the condition; otherwise, false.
Exceptions
ArgumentNullExceptionsourceorpredicateis null.
Remarks
The All method returns true if the sequence is empty.
If the sequence is empty, the predicate delegate is not invoked.
Usage Example
using System;
using System.Collections.Generic;
using System.Linq;
public class Example
{
public static void Main()
{
List<int> numbers = new List<int> { 2, 4, 6, 8, 10 };
bool allEven = numbers.All(n => n % 2 == 0);
Console.WriteLine($"All numbers are even: {allEven}"); // Output: All numbers are even: True
List<int> mixedNumbers = new List<int> { 1, 2, 3, 4, 5 };
bool allPositive = mixedNumbers.All(n => n > 0);
Console.WriteLine($"All numbers are positive: {allPositive}"); // Output: All numbers are positive: True
List<int> numbersWithNegative = new List<int> { 1, 2, -3, 4, 5 };
bool allPositiveAgain = numbersWithNegative.All(n => n > 0);
Console.WriteLine($"All numbers are positive: {allPositiveAgain}"); // Output: All numbers are positive: False
}
}