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Variables

Variable Declaration in C#

Used to declare a variable. Variables can be implicitly or explicitly typed.

Variables declared this way (without a static modifier) within classes are called instance variables. They belong to an instance of the class (i.e. an object).

Syntax

modifier dataType variableName; ///modifier is optional

///variables can be assigned values either separately or on declaration
variableName = value; ///separate line assignment

modifier dataType variableName = value; ///same line assignment

///implicitly typed variable
var variable2 = value;

Notes

The modifier (public, private) permits or restricts direct access to the variable with respect to its scope (class, method, etc.). Variables declared within a class are called fields.

Variables without a modifier are known as local variables, typically used within a method. They are temporary and only exist within the scope of the where its declared method.

dataType is the data type of the variable.

Example

public class Car { 
    private int speed; ///private variable declaration
    public int wheels; ///public variable declaration
    
    /*...constructor, etc...*/

    public void speedUp() {
        ///local variable declaration, in line assignment, only seen within speedUp method
        int speedIncrease = 10;
        speed += speedIncrease;
    }
}

See Also

Access Modifiers
Primitive Data Types

Types (C# Programming Reference) - MSDN