C# Data Types
C# Data Types
As explained in the variables chapter, a variable in C# must be a specified data type:
Example
int myNum = 5; // Integer (whole number)
double myDoubleNum = 5.99D; // Floating point number
char myLetter = 'D'; // Character
bool myBool = true; // Boolean
string myText = "Hello"; // String
A data type specifies the size and type of variable values.
It is important to use the correct data type for the corresponding variable; to avoid errors, to save time and memory, but it will also make your code more maintainable and readable. The most common data types are:
| Data Type | Size | Description |
|---|---|---|
| int | 4 bytes | Stores whole numbers from -2,147,483,648 to 2,147,483,647 |
| long | 8 bytes | Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
| float | 4 bytes | Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits |
| double | 8 bytes | Stores fractional numbers. Sufficient for storing 15 decimal digits |
| bool | 1 bit | Stores true or false values |
| char | 2 bytes | Stores a single character/letter, surrounded by single quotes |
| string | 2 bytes per character | Stores a sequence of characters, surrounded by double quotes |
Numbers
Number types are divided into two groups:
Integer types stores whole numbers, positive or negative (such as 123 or -456), without decimals.
Valid types are int
and long. Which type you should use, depends on the numeric value.
Floating point types represents numbers with a fractional
part, containing one or more decimals. Valid types are float and double.
Even though there are many numeric types in C#, the most used for numbers
are int (for whole numbers) and double (for floating point numbers). However, we will describe them all as you continue to
read.
Integer Types
Int
The int data type can store whole numbers from -2147483648 to 2147483647. In general, and in our tutorial, the int data type is
the preferred data type when we create variables with a numeric value.
Long
The long data type can store whole numbers from -9223372036854775808 to 9223372036854775807. This is used when int is not large enough to store the value. Note that you should end the value with an "L":
Floating Point Types
You should use a floating point type whenever you need a number with a decimal, such as 9.99 or 3.14515.
The float and double data types can store fractional numbers. Note that you should end the value with an "F" for floats and "D" for doubles:
Use float or double?
The precision of a floating point value indicates how many digits the value can have
after the decimal point.
The precision of float is only six or seven
decimal digits, while double variables have a precision
of about 15 digits. Therefore it is safer to use double for most calculations.
Scientific Numbers
A floating point number can also be a scientific number with an "e" to indicate the power of 10:
Example
float f1 = 35e3F;
double d1 = 12E4D;
Console.WriteLine(f1);
Console.WriteLine(d1);
Booleans
A boolean data type is declared with the bool keyword and can only take the values true or false:
Example
bool isCSharpFun = true;
bool isFishTasty = false;
Console.WriteLine(isCSharpFun); // Outputs True
Console.WriteLine(isFishTasty); // Outputs False
Boolean values are mostly used for conditional testing, which you will learn more about in a later chapter.
Characters
The char data type is used to store a
single character. The character must be
surrounded by single quotes, like 'A' or 'c':
Strings
The string data type is used to store a sequence of characters (text). String values must be surrounded by double quotes:
