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C# Variables


C# Variables

Variables are containers for storing data values.

In C#, there are different types of variables (defined with different keywords), for example:

  • int - stores integers (whole numbers), without decimals, such as 123 or -123
  • double - stores floating point numbers, with decimals, such as 19.99 or -19.99
  • char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
  • string - stores text, such as "Hello World". String values are surrounded by double quotes
  • bool - stores values with two states: true or false

Declaring (Creating) Variables

To create a variable, you must specify the type and assign it a value:

Syntax

type variableName = value;

Where type is a C# type (such as int or string), and variableName is the name of the variable (such as x or name). The equal sign is used to assign values to the variable.

To create a variable that should store text, look at the following example:

Example

Create a variable called name of type string and assign it the value "John":

string name = "John";
Console.WriteLine(name);

Try it Yourself »

To create a variable that should store a number, look at the following example:

Example

Create a variable called myNum of type int and assign it the value 15:

int myNum = 15;
Console.WriteLine(myNum);

Try it Yourself »

You can also declare a variable without assigning the value, and assign the value later:

Example

int myNum;
myNum = 15;
Console.WriteLine(myNum);

Try it Yourself »

Note that if you assign a new value to an existing variable, it will overwrite the previous value:

Example

Change the value of myNum to 20:

int myNum = 15;
myNum = 20; // myNum is now 20
Console.WriteLine(myNum);

Try it Yourself »


Other Types

A demonstration of how to declare variables of other types:

Example

int myNum = 5;
double myDoubleNum = 5.99D;
char myLetter = 'D';
bool myBool = true;
string myText = "Hello";

You will learn more about data types in a later chapter.