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
Learn about the char type and the byte type, and a bit about text encoding.
In this video,
we'll be using the C# interactive window,
0:00
which is a REPL feature
inside Visual Studio.
0:03
To open it up, we'll go to View >
Other Windows > C# Interactive.
0:07
Inside this window, we can execute C#
code like we can in a workspaces console.
0:14
I mentioned earlier that our
stream reader deals with encoding.
0:20
Let's take a look at our text file.
0:24
It contains a string called Hello, world!
0:27
So what is a string?
0:30
Well, a string is made up of one or
more characters.
0:31
That brings us to the char type.
0:35
The char is a type that
represents a single character.
0:38
The way we assign a value to a char
type in C# is similar to a string, but
0:41
instead of using double quotes,
we use single quotes.
0:45
So here's how we'd create a char variable.
0:49
char capitalH equals,
0:53
single quote, H, and semicolon.
0:56
capitalH.
1:02
Let's go find the documentation
on the char type.
1:05
C# char.
1:08
Here's something.
1:12
This page is for the keyword.
1:15
We can click on System.Char
to get to the actual type.
1:16
So check this out.
1:21
It's actually a struct and not a class.
1:23
A struct is a lot like a class,
but it has some limitations.
1:26
We'll get into a little more
about structs later on.
1:30
It says, Represents a character
as a UTF-16 code unit.
1:33
So what does it mean by UTF-16 code unit?
1:39
UTF-16 is a Unicode
character encoding format.
1:42
Without going into too much detail,
It's good to keep in mind that
1:47
every piece of text, even every character,
has some kind of encoding behind it.
1:50
This is because computers only
know how to deal with numbers, and
1:56
they need some way to translate
the numbers into characters.
1:59
Encoding formats are kind of like
the Rosetta Stone for computers.
2:03
Unicode formats have many characters in
their sets, and each character has a code,
2:07
sometimes called a control code or
a codepoint.
2:12
This is so we can accommodate languages
that have way more characters than
2:16
the standard English alphabet.
2:20
Let's look up the Unicode character for
the lower letter h.
2:22
Do unicode letter h.
2:26
All right, here's the capital letter H.
2:30
Let's see if we can get to it from there.
2:32
Lowercase, U+0068.
2:36
We can use this value to
create a char variable.
2:39
We'll do char lowerH equals,
single quote, and then a backslash,
2:45
u, and then I'll paste in that
code we copied from the web page.
2:52
The backslash is indicating an escape
sequence like in our directory string,
2:58
and the 0068 is a hexadecimal value
that represents our lower letter h.
3:03
Each character in C# is encoded as two
bytes in the default encoding of UTF-16.
3:08
lowerH.
3:14
Let's try getting the underlying
bytes of our lower letter h.
3:18
byte[] unicodeBytes.
3:21
First we'll need to specify an encoding.
3:26
So UnicodeEncoding and
3:28
Unicode.GetBytes.
3:31
And it wants a character array, so
I'll pass it new character array.
3:38
And we'll fill it with the lowerH.
3:44
Okay, let's see what it's got.
3:50
And there's our two bytes.
3:54
Now we can convert them
back into a string.
3:56
string unicodeString equals
3:59
UnicodeEncoding.Unicode.GetString, and
4:03
we'll pass it the unicodeBytes.
4:10
And Unicode string has our letter h.
4:16
And notice it's a string because,
it's got double quotes.
4:22
So what is the byte type exactly?
4:26
In C#, a byte is an integral type,
an unsigned eight-bit integer.
4:28
Integral types represent whole numbers and
have a minimum and a maximum value.
4:33
Unsigned means that it can
only contain positive values.
4:39
An unsigned eight-bit integer
can store values from 0 to 255.
4:43
Conversely, when you see that a type is
signed, it means that it can have a range
4:48
of values from a negative
number to a positive number.
4:52
A signed byte in C#, declared as sbyte,
is also eight-bit, but
4:55
it can have a minimum value of a negative
128 and a maximum value of 127.
5:00
Let's create one.
5:06
sbyte signedByte = -128.
5:07
If we tried to assign it a constant
value that's out of range, like 200,
5:14
the compiler wouldn't let us.
5:19
Let's try it.
5:21
sbyte signedByte = 200.
5:22
We'll get into other signed and unsigned
integral types later in this course.
5:29
How about a character that's not usually
on a keyboard, like the degree symbol,
5:34
the unit symbol for a temperature?
5:38
Let's go look it up.
5:41
Unicode degree symbol.
5:43
Here it is.
5:45
00B0.
5:49
Gonna copy that with Ctrl+C.
5:52
Get back to our code.
5:56
So here I'll say char degree equals,
single quote,
5:57
backslash, u, and I'll paste in
our code from the Unicode page.
6:02
Okay, now let's see what it looks
like when the console prints it out.
6:09
Console.WriteLine.
6:13
We'll type a sentence,
The current temperature
6:15
is 74.6,
then we'll insert our degree symbol.
6:22
Whoops, I got an equal sign in here,
6:29
needs to be a plus, Fahrenheit.
6:34
The current temperature is
74.6 degrees Fahrenheit.
6:42
In the .NET framework,
when strings are created in memory,
6:46
their default encoding is UTF-16.
6:50
You'll also see UTF-8, which is
usually the encoding for text files.
6:53
In IO, we can specify different
encodings if we need to.
6:58
But you usually don't have to worry
about it unless you're dealing with
7:01
communicating with other systems
that may need a different encoding.
7:04
Check out the notes if you want to read
more about different encodings in .NET.
7:07
You need to sign up for Treehouse in order to download course files.
Sign up