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C# | Array.FindAll() Method

  • Last Updated : 01 Feb, 2019

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:




// C# program to demonstrate
// FindAll() method
using System;
using System.Collections.Generic;
  
public class GFG {
  
// Main Method
public static void Main()
{
  
    try {
  
        // Creating and intializing 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
// PrintIndexAndValues
public static void PrintIndexAndValues(String[] myArr)
{
    for (int i = 0; i < myArr.Length; i++) {
  
        Console.WriteLine("{0}", myArr[i]);
    }
    Console.WriteLine();
}
}
Output:
Initial Array:
Sun
Mon
Tue
Sat

Elements are: 
Sun
Sat

Example 2:




// C# program to demonstrate
// FindAll() method
// For ArgumentNullException
using System;
using System.Collections.Generic;
  
public class GFG {
  
// Main Method
public 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
// PrintIndexAndValues
public static void PrintIndexAndValues(String[] myArr)
{
    for (int i = 0; i < myArr.Length; i++) {
  
        Console.WriteLine("{0}", myArr[i]);
    }
    Console.WriteLine();
}
}
Output:
Trying to get the element from a null array

Exception Thrown: System.ArgumentNullException

Reference:




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