C# | Array.FindAll() Method - GeeksforGeeks

06 Oct, 2021
This method is used to retrieve all the elements that match the conditions defined by the specified predicate.Syntax:  
public static T[] FindAll (T[] array, Predicate match);
Here, T is the type of element of the array.Parameters:  
array: It is the one-dimensional, zero-based array to search.match: It is the predicate that defines the conditions of the element to search for.  
Return Value: This method return an array containing all elements that matches the conditions defined by the specified predicate if it is found. Otherwise, it returns an empty array.Exception: This method throws ArgumentNullException if the array is null or match is null.Below programs illustrate the use of Array.FindAll(T[], Predicate) Method:Example 1: 
CSharp
// C# program to demonstrate// FindAll() methodusing System;using System.Collections.Generic; public class GFG { // Main Methodpublic static void Main(){     try {         // Creating and initializing new the String        String[] myArr = {"Sun", "Mon", "Tue", "Sat"};         // Display the values of the myArr.        Console.WriteLine("Initial Array:");         // calling the PrintIndexAndValues()        // method to print        PrintIndexAndValues(myArr);         // getting a element a with required        // condition using method Find()        String[] value = Array.FindAll(myArr,               element => element.StartsWith("S",               StringComparison.Ordinal));         // Display the value        // of the found element.        Console.WriteLine("Elements are: ");         // printing the Array of String        PrintIndexAndValues(value);    }    catch (ArgumentNullException e) {         Console.Write("Exception Thrown: ");        Console.Write("{0}", e.GetType(), e.Message);    }} // Defining the method// PrintIndexAndValuespublic static void PrintIndexAndValues(String[] myArr){    for (int i = 0; i < myArr.Length; i++) {         Console.WriteLine("{0}", myArr[i]);    }    Console.WriteLine();}}
Initial Array:
Sun
Mon
Tue
Sat

Elements are: 
Sun
Sat
 
Example 2: 
CSharp
// C# program to demonstrate// FindAll() method// For ArgumentNullExceptionusing System;using System.Collections.Generic; public class GFG { // Main Methodpublic static void Main(){     try {         // Creating and initializing        // new the String        String[] myArr = null;         // getting a element a with        // required condition using        // method Find()        Console.WriteLine("Trying to get the element from a null array");        Console.WriteLine();        String[] value = Array.FindAll(myArr,                  element => element.StartsWith("S",                  StringComparison.Ordinal));         // Display the value of the found element.        Console.WriteLine("Elements are: ");         // printing the Array of String        PrintIndexAndValues(value);    }     catch (ArgumentNullException e) {         Console.Write("Exception Thrown: ");        Console.Write("{0}", e.GetType(), e.Message);    }} // Defining the method// PrintIndexAndValuespublic static void PrintIndexAndValues(String[] myArr){    for (int i = 0; i < myArr.Length; i++) {         Console.WriteLine("{0}", myArr[i]);    }    Console.WriteLine();}}
Trying to get the element from a null array

Exception Thrown: System.ArgumentNullException
 
Reference:  
https://docs.microsoft.com/en-us/dotnet/api/system.array.findall?view=netframework-4.7.2
 
simranarora5sos
CSharp-Arrays
CSharp-method
C#
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
C# | Delegates
C# | Abstract Classes
Extension Method in C#
C# | Replace() Method
C# | Class and Object
C# | Constructors
Introduction to .NET Framework
C# | Data Types
C# | Encapsulation
Common Language Runtime (CLR) in C#