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How to mark a method as Obsolete or Deprecated in C# ?


This blog post will explain in simple steps on how you can mark a method or function obsolete in C# or “deprecated” in C# using the Obsolete keyword.

How to mark a method as Obsolete or Deprecated in C# ?

For Example :

public class Employee
{

        public string Name { get; set; }

        public void SetEmployeeName(string name)
        {
            Name = name;

        }

}

If you need to mark the method SetEmployeeName as deprecated , then , just include the obsolete attrbute before the function like this

public class Employee
{
    public string Name { get; set; }

    [ Obsolete  ]
    public void SetEmployeeName(string name)
    {
        Name = name;

    }

}

When you call the SetEmployeeName , it should only show a warning stating the method is obsolete .

How to mark a method as Obsolete or Deprecated in C# ?

You can add an description for the function too via

[Obsolete("SetEmployeeName is deprecated,Use a different method instead", true) ]  ] 
public void SetEmployeeName(string name)
{

    Name = name;

}

The second parameter(true) defines to throw compiler error when this function is called .

How to mark a method as Obsolete or Deprecated in C# ?

Reference

Senthil Kumar B
Senthil Kumar is a former Microsoft MVP (Most Valuable Professional). He is a Co-Author of the book "Windows 10 Development Recipes using JavaScript and CSS" for Apress Publication. He is a technical presenter, blogger, mentor and a Geek.  Senthil is a regular speaker is various local user groups. He has presented at conferences like Great Indian Developer Summit (GIDS) & Microsoft DevCamps. You can reach out to him via his Twitter handle @isenthil.