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?

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?

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"