Any and All
Learn condition checks with Any and All.
Condition checks with Any and All
The Any method asks whether at least one element in the collection matches a condition. It returns true or false. numbers.Any(n => n > 100) checks if there is at least one large number.
The All method expects every element to match. numbers.All(n => n > 0) asks if all numbers are positive. Both return bool; they short-circuit and stop at the first matching or non-matching element.
Any versus All
Any is like a logical OR: one match is enough. All is like a logical AND: one non-match makes it false. On an empty collection, Any returns false and All returns true (a vacuous truth).
A parameterless Any() tells whether the collection is non-empty: list.Any() returns true when the list has elements. This is more efficient than list.Count > 0 because it does not count; it just checks for at least one.
Exercise Is there a negative?
Check whether the numbers array has at least one negative number using Any and print the result with Console.WriteLine.
Show example solution
Query with numbers.Any(n => n < 0), store the result, print with Console.WriteLine.
Example solution:
using System;
using System.Linq;
class Program
{
static void Main()
{
int[] numbers = { 3, 7, -2, 8 };
var has = numbers.Any(n => n < 0);
Console.WriteLine(has);
}
}Test yourself
-
When does Any return true?
new[] { 1, 2, 3 }.Any(n => n > 2);- Never
- When at least one element matches the condition
- When all elements match
- When the collection is empty
Show answer
Never — Correct. Any returns true when at least one element matches; in the example 3 > 2 so it returns true.
-
Complete the Any call
bool hasBig = numbers.____(n => n > 100);Show answer
bool hasBig = numbers.Any(n => n > 100); -
Match each method to its behavior
- Any
- At least one matches
- All
- All match
- Any()
- Is non-empty
- All(n => n > 0)
- All positive