8.3. Array Methods

As with strings, C# provides us with useful methods for arrays. These methods will either alter an existing array, return information about the array, or create and return a new array.

8.3.1. Common Array Methods

Here is a sample of the most frequently used array methods. More complete lists can be found here:

  1. Microsoft Array Methods
  2. Geeks for Geeks Array Methods

To see detailed examples for a particular method, control-click (or right-click) on its name.

Methods That Return Information About The Array
Method Syntax Description
IndexOf Array.IndexOf(arrayName, item) Returns the index of the FIRST occurrence of an item in the array.
LastIndexOf Array.LastIndexOf(arrayName, item) Returns the index of the LAST occurrence of an item in the array. If the item is not in the array, -1 is returned.
GetValue arrayName.GetValue(index) Returns the value of specified index.
Methods That Rearrange The Entries In The Array
Method Syntax Description
Reverse Array.Reverse(arrayName) Reverses the order of the elements in an array.
Sort Array.Sort(arrayName) Arranges the elements of an array into increasing order.
Methods That Add Or Remove Values From An Array
Method Syntax Description
Resize Array.Resize(ref arrayName, desiredLength) Adds of Removes indicies based on desiredLength value.
Methods That Update Values Within An Array
Method Syntax Description
SetValue arrayName.SetValue(new item, index) Updates index value with new item.
Copy Array.Copy(originalArray, copiedArray, numItems) Updates index value with new item.
String Methods That Update Array Values
Method Syntax Description
Join string.Join("connecter", arrayName) Combines all the elements of an array into a string.
Split stringName.Split("delimiter") Divides a string into smaller string pieces, which are stored in a new array.
ToCharArray stringName.ToCharArray() Divides a string into chars, which are stored in a new array.

8.3.2. Check Your Understanding

Follow the links in the table above for the Sort, Reverse, Split and Join methods. Review the content and then answer the following questions.

Question

What is printed by the following code?

1
2
3
4
5
6
7
string[] charles = {"coder", "Tech", "47", "23", "350"};
Array.Sort(charles);
Console.WriteLine(charles[0]);
Console.WriteLine(charles[1]);
Console.WriteLine(charles[2]);
Console.WriteLine(charles[3]);
Console.WriteLine(charles[4]);
  1. "350", "23", "47", "Tech", "coder"
  2. "coder", "Tech", "23", "47", "350"
  3. "23", "47", "350", "Tech", "coder"
  4. "23", "350", "47", "coder", "Tech"

Question

Which statement converts the string string phrase = "LaunchCode students rock!" into the array string[] words = {"LaunchCode", "students", "rock!"}?

  1. string.Join(" ", phrase);
  2. phrase.Split(" ");
  3. string.Join("", phrase);
  4. phrase.Split("");

Question

What is printed by the following program?

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
string[] groceryBag = {"bananas", "apples", "edamame", "chips", "cucumbers", "milk", "cheese"};
string[] selectedItems = new string[4];

Array.Copy(groceryBag, selectedItems, 4);
Array.Sort(selectedItems);

Console.WriteLine(selectedItems[0]);
Console.WriteLine(selectedItems[1]);
Console.WriteLine(selectedItems[2]);
Console.WriteLine(selectedItems[3]);
  1. "apples", "bananas", "edamame", "chips"
  2. "chips", "cucumbers", "edamame", "milk"
  3. "apples", "banana", "chips", "edamame"
  4. "cheese", "chips", "cucumbers", "edamame"