This course will be retired on June 1, 2025.
Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Preview
Start a free Courses trial
to watch this video
Collections are used to organize data so that it can be used efficiently.
Related Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign upRelated Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign up
Hello and welcome to C# collections.
0:04
I'm Jeremy in this course will be learning
0:07
all about how to work with data
in various types of collections.
0:10
Collections are used to organize data so
that they can be used efficiently.
0:14
A more common term for
a collection is a data structure and
0:18
you'll find that I use
the terms interchangeably.
0:22
In C# we call them collections.
0:25
It's very difficult to write
any sort of software program
0:28
without using a collection at least once.
0:31
In fact,
if you've taken the prerequisites for
0:33
this course,
then you're already familiar with arrays.
0:36
An array is a type of collection.
0:39
You may have also heard of lists,
sets, and dictionaries.
0:42
These are the most common
types of collections.
0:45
Although the title of this
course is C# collections.
0:48
The collections we'll discuss here are all
actually provided by the .NET framework,
0:51
which means they can be
used by any .NET language.
0:57
We'll be using C# as we explore them.
1:00
There are dozens of different
types of collections.
1:03
You might be wondering why there are so
many different types.
1:06
They each have advantages and
disadvantages.
1:09
Basically most collections support
four fundamental operations,
1:13
Insert, Access and Find,
Update, and Delete.
1:18
One way we can evaluate a collection
is by how quickly it can perform
1:23
each of these operations.
1:27
So when we decide which one to use,
we should consider when and
1:29
how often we need to
perform these operations.
1:34
Because the job of a collection is
to store data efficiently, we also
1:37
want to consider how much additional space
it needs in order to store each item.
1:41
The amount of data the collection
will store is also a factor.
1:46
Some are efficient for
1:50
small to medium amounts of data, and
others are better for larger sets.
1:51
Additionally some collections can store
items in the order we add them and
1:55
others, can't.
1:59
So if we want to maintain
an ordered list of items,
2:00
we probably want to pick the collection
that can do that for us.
2:04
Something else to consider is how quickly
we can copy the items from one collection
2:08
into another.
2:12
This is actually very important
because the way we store
2:14
data in our programs while
we're working with it
2:17
is often different than the way that
the data is displayed to a user.
2:19
As you can see,
2:24
there are many things to consider
when picking which collection to use.
2:25
You may be thinking,
this seems like a lot of hassle.
2:29
Isn't there a collection out there
that we can use for everything?
2:32
The answer to that question depends
on how much data you're working with.
2:36
If you're only storing a few items and
the amount of data isn't going to grow,
2:40
then it doesn't really matter
which collection you use.
2:44
Just pick the one that
simplest to work with.
2:47
Picking the correct collection for
2:51
the job doesn't really become important
until the amount of data you're working
2:52
with starts to affect
the performance of the computer.
2:56
However, it's sometimes
difficult to predict
2:59
how much data a program will
have to deal with in the future.
3:02
A couple dozen items in
a collection may not be a big deal.
3:05
Depending on how often it's being used but
3:09
it's not uncommon to be working
with thousands of items or
3:12
even larger collections, especially in the
age of big data sets that we live in now.
3:15
That's just one more thing to
consider when picking a collection.
3:20
I found it important to know about many
different types of collections, so
3:24
that I can pick the right one for the job.
3:28
In fact a very common question
asked in job interviews
3:30
is which collection would you use
to solve a given problem and why.
3:34
In this course we'll learn about four
of the most common types of collections
3:38
arrays, lists, sets, and dictionaries.
3:43
Learning how these work can
help you start to understand
3:47
how other types of
collections work as well.
3:50
In the end of this course, we'll use what
we've learned to create an application
3:53
that translates text into Morse
code messages and back again.
3:57
To start,
let's take a deeper look at arrays in C#
4:01
You need to sign up for Treehouse in order to download course files.
Sign upYou need to sign up for Treehouse in order to set up Workspace
Sign up