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this

The this keyword refers to the current instance of the class. Static member functions do not have a this pointer. The this keyword can be used to access members from within constructors, instance methods, and instance accessors.

The following are common uses of this:

  • To qualify members hidden by similar names, for example:
    public Employee(string name, string alias) 
    {
       this.name = name;
       this.alias = alias;
    }
    
  • To pass an object as a parameter to other methods, for example:
    CalcTax(this);
    
  • To declare indexers, for example:
    public int this [int param]
    {
          get
          {
             return array[param];
          }
          set
          {
             array[param] = value;
          }
       }
    

It is an error to refer to this in a static method, static property accessor, or variable initializer of a field declaration.

Example

In this example, this is used to qualify the Employee class members, name and alias, which are hidden by similar names. It is also used to pass an object to the method CalcTax, which belongs to another class.

// keywords_this.cs
// this example
using System;
public class Employee 
{
   public string name;
   public string alias;
   public decimal salary = 3000.00m;

   // Constructor:
   public Employee(string name, string alias) 
   {
      // Use this to qualify the fields, name and alias:
      this.name = name;
      this.alias = alias;
   }

   // Printing method:
   public void printEmployee() 
   {
      Console.WriteLine("Name: {0}\nAlias: {1}", name, alias);
      // Passing the object to the CalcTax method by using this:
      Console.WriteLine("Taxes: {0:C}", Tax.CalcTax(this));
   }
}
public class Tax 
{
   public static decimal CalcTax(Employee E) 
   {
      return (0.08m*(E.salary));
   }
}

public class MainClass 
{
   public static void Main() 
   {
      // Create objects:
      Employee E1 = new Employee ("John M. Trainer", "jtrainer");

      // Display results:
      E1.printEmployee();
   }
}

Output

Name: John M. Trainer
Alias: jtrainer
Taxes: $240.00

For additional examples, see class and struct.

See Also

C# Keywords | base

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