How to delete an element from an array in C#

int[] numbers = { 1, 3, 4, 9, 2 }; numbers = numbers.Except(new int[]{4}).ToArray(); 

You can also convert your array to a list and call remove on the list. You can then convert back to your array.

int[] numbers = {1, 3, 4, 9, 2}; var numbersList = numbers.ToList(); numbersList.Remove(4); 

The code that is written in the question has a bug in it

Your arraylist contains strings of " 1" " 3" " 4" " 9" and " 2" (note the spaces)

So IndexOf(4) will find nothing because 4 is an int, and even "tostring" would convert it to of "4" and not " 4", and nothing will get removed.

An arraylist is the correct way to go to do what you want.

I posted my solution here.

This is a way to delete an array element without copying to another array - just in frame of the same array instance:

 public static void RemoveAt<T>(ref T[] arr, int index) { for (int a = index; a < arr.Length - 1; a++) { // moving elements downwards, to fill the gap at [index] arr[a] = arr[a + 1]; } // finally, let's decrement Array's size by one Array.Resize(ref arr, arr.Length - 1); } 

Removing from an array itself is not simple, as you then have to deal with resizing. This is one of the great advantages of using something like a List<int> instead. It provides Remove/RemoveAt in 2.0, and lots of LINQ extensions for 3.0.

If you can, refactor to use a List<> or similar.

Balabaster's answer is correct if you want to remove all instances of the element. If you want to remove only the first one, you would do something like this:

int[] numbers = { 1, 3, 4, 9, 2, 4 }; int numToRemove = 4; int firstFoundIndex = Array.IndexOf(numbers, numToRemove); if (numbers >= 0) { numbers = numbers.Take(firstFoundIndex).Concat(numbers.Skip(firstFoundIndex + 1)).ToArray(); } 

As a generic extension, 2.0-compatible:

using System.Collections.Generic; public static class Extensions { //========================================================================= // Removes all instances of [itemToRemove] from array [original] // Returns the new array, without modifying [original] directly // .Net2.0-compatible public static T[] RemoveFromArray<T> (this T[] original, T itemToRemove) { int numIdx = System.Array.IndexOf(original, itemToRemove); if (numIdx == -1) return original; List<T> tmp = new List<T>(original); tmp.RemoveAt(numIdx); return tmp.ToArray(); } } 

Usage:

int[] numbers = {1, 3, 4, 9, 2}; numbers = numbers.RemoveFromArray(4); 

You can do in this way:

int[] numbers= {1,3,4,9,2}; List<int> lst_numbers = new List<int>(numbers); int required_number = 4; int i = 0; foreach (int number in lst_numbers) { if(number == required_number) { break; } i++; } lst_numbers.RemoveAt(i); numbers = lst_numbers.ToArray(); 

' To remove items from string based on Dictionary key values. ' VB.net code

 Dim stringArr As String() = "file1,file2,file3,file4,file5,file6".Split(","c) Dim test As Dictionary(Of String, String) = New Dictionary(Of String, String) test.Add("file3", "description") test.Add("file5", "description") stringArr = stringArr.Except(test.Keys).ToArray() 

In recent C#/.NET featuring the Span<T> type and range expressions this can be done using the Span.CopyTo method to move array elements around:

// Removes a[i..i+n], fast but not preserving the order of array elements. void arrayRemoveAtFast<T>(ref T[] a, int i, int n) { // Create a Span that references the array elements. var s = a.AsSpan(); // Copy the last n array elements to positions i…i+n. // Caveat: Use `s`, not `a`, or else the result may be invalid. s[^n..].CopyTo(s[i..(i+n)]); // Cut the last n array elements off. a = a[..^n]; } // Removes a[i..i+n], preserving the order of array elements. void arrayRemoveAtPreserveOrder<T>(ref T[] a, int i, int n) { // Create a Span that references the array elements. var s = a.AsSpan(); // Move array elements that follow the ones to remove to the front. // Caveat: Use `s`, not `a`, or else the result may be invalid. s[(i + n)..].CopyTo(s[i..^n]); // Cut the last n array elements off. a = a[..^n]; } 

 public int[] DeletePart(int position, params int[] numbers) { int[] result = new int[numbers.Length - 1]; int z=0; for (int i = 0; i < numbers.Length; i++) { if (position - 1 != i) { result[z] = numbers[i]; z++; } } return result; }