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Flags Attribute In Enums C#

In this article I will explain about Flags attribute in enums.

Software Requirement

Before you start reading this tutorial you should make sure that visual studio (any version) is installed on your machine.

What Is The Purpose Of The Flags Attribute?

Adding the Flags attribute to the Enums means that enumerations will be treated as bit fields.

Syntax

[Flags]
public enum Enum_Name {}

Example

Consider a scenario where you are working on an application for the election commission. In the application, the eligibility criteria of the candidate who is participating in the election are: -

Above 18 years of age
A resident of that country
A graduate
Without criminal background

To implement the above scenario, you write the following method: -

public bool IsEligibleToContestElection(bool above18, bool resident, bool graduate, bool nocriminalbackground) {
  if (above18 == true && resident == true && graduate == true && nocriminalbackground == true) return true;
  else return false;
}

And this is how you call this method.

IsEligibleToContestElection(true, true, true, true)

The above code looks fine. But in case the election commission asks you to add 10 more criteria for the eligibility of the candidate. Then you are required to change the code and add 10 more input parameters to the function (or maybe function overloading). So, you will end up with a function with multiple parameters which means that your code is not clean and is difficult to manage.

A very simple solution to the problem is to use an enum with a Flags attribute. So, the above code could be rewritten as: -

[Flags]
public enum EligibilityCriteria {
  Above18,
  IsResident,
  AGraduate,
  NoCriminalBackground
}

public bool IsEligibleToContestElection(EligibilityCriteria criteria) {
  if (criteria == (EligibilityCriteria.Above18 & EligibilityCriteria.IsResident & EligibilityCriteria.AGraduate & EligibilityCriteria.NoCriminalBackground)) return true;
  else return false;
}

And this is how you can call this method.

IsEligibleToContestElection(EligibilityCriteria.Above18 & EligibilityCriteria.IsResident & EligibilityCriteria.AGraduate & EligibilityCriteria.NoCriminalBackground)

So, the code is cleaner and easy to manage.

Posted By -	Karan Gupta

Posted On -	Wednesday, October 29, 2014

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