In this tutorial, we would learn about static keyword in c# programming language.
static : something which belongs to the type itself, not with an instance of the type.
The modifier in C# language applies to the following :
Variable
Methods
Class
Constructor
Now we would look at examples of each
static variable
static variables are accessed with the name of the class.
Only a single copy of the variable is created and shared among all the instances of the class.
static variable can't be accessed with the instance.
var can not be used to declare a static variable, one must specify the type of variable after the static keyword.
public class Employee{
public static int EmpCount = 0;
public void AddEmployee(){
EmpCount++;
}
}
public static void Main(string[] args){
Console.WriteLine("Start Of the Program");
Employee emp1 = new Employee();
emp1.AddEmployee();
Console.WriteLine(Employee.EmpCount);
Employee emp2 = new Employee();
emp2.AddEmployee();
Console.WriteLine(Employee.EmpCount);
Console.WriteLine(emp2.EmpCount);
Console.ReadKey();
}
static method
Similar to static variables, static methods are also accessed with the name of the class.
static methods could use both static and non-static class members.
static members are directly accessed inside the static method without a class name, and non-static members are accessed using instances.
public class Employee {
private string FirstName;
private string LastName;
public Employee(string firstName, string lastName) {
FirstName = firstName;
LastName = lastName;
}
public string FullName {
get{
return ($"{this.FirstName} {this.LastName}");
}
}
public static int EmpCount = 0;
public static void AddEmployee(Employee emp) {
EmpCount++;
Console.WriteLine(emp.FullName);
}
}
public static void Main(string[] args) {
Console.WriteLine("Start Of the Program");
Employee emp1 = new Employee("John", "Smith");
Employee.AddEmployee(emp1);
Console.WriteLine(Employee.EmpCount);
Employee emp2 = new Employee("John", "Bold");
Employee.AddEmployee(emp2);
Console.WriteLine(Employee.EmpCount);
Console.ReadKey();
}
static constructor
a static constructor is used to initialize static data or to perform an action that needs to be performed only once.
A class can have only one static constructor.
No parameter, No access modifier, No inheritance or overloading
static methods could use both static and non-static class members.
a static constructor is called automatically by the CLR. The user has no control over when a static constructor is executed in the program. static constructor runs before the instance constructor.
a static constructor is called only for a single time during program execution.
public class Organization {
static Organization() {
Console.WriteLine("Static constrctor called");
}
public Organization() {
Console.WriteLine("Instance constructor called");
}
}
public static void Main(string[] args) {
Console.WriteLine("Start Of the Program");
Organization org1 = new Organization();
Console.ReadKey();
}
** Output **
Start Of the Program
Static constrctor called
Instance constructor called
static class
static class can only contain static data members, static methods and static constructor. [Error if there are non-static fields, the non-static method in static class]
Instances can not be created for a static class. [Error if user tries to create an instance of static class]
static classes are sealed, they can't be inherited.
static members can be accessed directly without using the class name inside the static class.
public static class Organization {
private static string FounderName = "James Clark";
private static DateTime StartDate = new DateTime(1990, 01, 01);
public static string Introduction;
static Organization() {
Introduction = $"This organization was founded by {FounderName} in {StartDate.Year}";
}
}
public static void Main(string[] args) {
Console.WriteLine("Start Of the Program");
Console.WriteLine(Organization.Introduction);
}
** Output **
Start Of the Program
This organization was founded by James Clark in 1990.
In this post, we have learned about static keyword in c#. Please share your feedback and suggestios to improve this.
