When you declare variables in your programs, you must indicate to the compiler the type and the name of the variables. There are many variable types and derivations of them. A type defines the amount of data a variable can store, and the set of operations the program can perform on those data.
C# accepts the following base types, also known as primitive types, with the exception of string, which is a derived type:
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
TYPE
ALIAS FOR
ALLOWED VALUES
================================================================================================
integer numbers variables
int
System.Int32
Integer between −2147483648 and 2147483647
byte
System.Byte
Integer between 0 and 255
floating point numbers variables
float
System.Single
7 digits (32 bit)
double
System.Double
15-16 digits (64 bit)
decimal
System.Decimal
28-29 significant digits (128 bit)
text variables
string
System.String
A sequence of characters
char
System.Char
Single Unicode character, stored as an integer between 0 and 65535
boolean variables
bool
System.Boolean
Boolean value, true or false
|
Additional Information
There are a lot of other types extending on these variables, that are not used as much, or they are used in special cases. While it is unlikely you will be using them any time soon, you should take a look over them to familiarize yourself with their keyword names:
|
1
2
3
4
5
6
7
8
|
TYPE
ALIAS FOR
ALLOWED VALUES
==========================================================================================
short
System.Int16
Integer between −32768 and 32767
ushort
System.UInt16
Integer between 0 and 65535
uint
System.UInt32
Integer between 0 and 4294967295
long
System.Int64
Integer between −9223372036854775808 and 9223372036854775807
ulong
System.UInt64
Integer between 0 and 18446744073709551615
sbyte
System.SByte
Integer between −128 and 127
|
The u in some keywords stands for unsigned, meaning that the variable uses the sign bit to further store relevant digits, in which case it can store only positive values or 0, but in a greater range. The s in sbyte means signed byte, and, as we will later learn, a byte variable does not have a sign bit; in this case, sbyte is a
byte variable that uses a sign bit. This will be further explained in a future lesson.
In the next lesson we will learn how we can give values to our variables.
The concepts explained in this lesson are also shown visually as part of the following video:
