The ability to work with any programming language requires a

good understanding of the data types it offers in order to comprehend the

language’s possibilities and limitations. In this article, I look at the

characteristics and specifics of C# data types as a way for developers to have

a better grasp of what the language has to offer.

C# allows you to define two types of variables: value types

and reference types. The value types hold actual values, while reference types

hold references to values stored somewhere in memory. Value types are allocated

on the stack and are available in most programming languages. Reference types

are allocated on the heap and typically represent class instances. C# also

allows defining your own value and reference types in the code. All value and

reference types are derived from a base type called *object*. C# also lets you to convert from one type to another

through either implicit (don’t result in the loss of data) or explicit (may

result in loss of data/precision) conversions.

## Predefined C# value types

**sbyte****:**Holds 8-bit signed integers. The

s in sbyte stands for signed, meaning that the

variable’s value can be either positive or negative. The smallest possible

value for ansbyte

variable is -128; the largest possible value is 127.**byte****:**Holds 8-bit unsigned integers.

Unlike sbyte variables, byte variables are not

signed and can only hold positive numbers. The smallest possible value for

a byte variable is 0; the largest possible value is 255.**short****:**Holds 16-bit signed integers. The

smallest possible value for a short variable is -32,768; the largest

possible value is 32,767.**ushort****:**Holds 16-bit unsigned integers.

The u in ushort stands for unsigned. The

smallest possible value of an ushort variable is

0; the largest possible value is 65,535.**int****:**Holds 32-bit signed integers.

The smallest possible value of an int variable

is -2,147,483,648; the largest possible value is 2,147,483,647.**uint****:**Holds 32-bit unsigned integers.

The u in uint stands for unsigned. The smallest

possible value of a uint variable is 0; the

largest possible value is 4,294,967,295.**long****:**Holds 64-bit signed integers.

The smallest possible value of a long variable is

9,223,372,036,854,775,808; the largest possible value is

9,223,372,036,854,775,807.**ulong****:**Holds 64-bit unsigned integers.

The u in ulong stands for unsigned. The smallest

possible value of a ulong

variable is 0; the largest possible value is 18,446,744,073,709,551,615.**char****:**Holds 16-bit Unicode characters.

The smallest possible value of a char variable is the Unicode character

whose value is 0; the largest possible value is the Unicode character

whose value is 65,535.**float****:**Holds a 32-bit signed

floating-point value. The smallest possible value of a float type is

approximately 1.5 times 10 to the 45th power; the largest possible value

is approximately 3.4 times 10 to the 38th power.**double****:**Holds a 64-bit signed

floating-point value. The smallest possible value of a double is

approximately 5 times 10 to the 324th; the largest possible value is approximately

1.7 times 10 to the 308th.**decimal****:**Holds a 128-bit signed

floating-point value. Variables of type decimal are good for financial

calculations. The smallest possible value of a decimal type is approximately

1 times 10 to the 28th power; the largest possible value is approximately

7.9 times 10 to the 28th power.**bool****:**Holds one of two possible values,

true or false. The use of the bool type is one

of the areas in which C# breaks from its C and C++ heritage. In C and C++,

the integer value 0 was synonymous with false, and any nonzero value was

synonymous with true. In C#, however, the types are not synonymous. You

cannot convert an integer variable into an equivalent bool

value. If you want to work with a variable that needs to represent a true

or false condition, use a bool variable and not

an int variable.

## Predefined C# reference types

**string****:**Represents a string of Unicode

characters. It allows easy manipulation and assignment of strings. Strings

are immutable, meaning that once it is created it can’t be modified. So

when you try to modify a string, such as concatenating it with another

string, a new string object is actually created to hold the new resulting

string.**object****:**Represents a general purpose

type. In C#, all predefined and user-defined types inherit from the object

type or System.Object class.

## Summary

Proper utilization of correct data types allows developers

to make the most of the language, but may take some time for those who have

used different programming languages prior to switching to C#. For more

information about each type, visit the Microsoft Web

site.

*Irina Medvinskaya has been involved in technology since 1996. She has an MBA from Pace University and works as a Project Manager at Citigroup.*