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“Required” Keyword in C#

Jay Krishna Reddy 19

“Required” Keyword in C#

Jay Krishna Reddy
Level Up Coding
Published in
3 min read2 days ago

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Photo by Caftos on Unsplash

In C#, the required keyword is used to define dependencies between different parts of code. This keyword is often used in combination with using statements to ensure that all the necessary resources are available at runtime. In this article, we will discuss the required keyword in detail and provide clear examples of its usage.

The required keyword is used to specify that a particular directive or assembly reference is required for the code to compile and run correctly. It is used in conjunction with the using statement, which is used to include namespaces in your code. When you mark a namespace with the required keyword, you are telling the compiler that the code requires that namespace to be available at runtime.

Let’s take an example to better understand this concept. Consider the following code:

using System;

namespace MyNamespace
{
class MyClass
{
static void Main()
{
Console.WriteLine("Hello World!");
}
}
}

In this example, we have included the System namespace using the using statement. However, we have not marked it as required. This means that if the System namespace is not available at runtime, the code will still compile, but it will fail at runtime. To avoid this, we should mark the System namespace as required by adding the required keyword before the using statement:

required using System;

namespace MyNamespace
{
class MyClass
{
static void Main()
{
Console.WriteLine("Hello World!");
}
}
}

Now, if the System namespace is not available at runtime, the code will not compile. This will prevent any runtime errors and ensure that the code works as expected.

The required keyword can also be used with assembly references. Consider the following code:

using System;

namespace MyNamespace
{
class MyClass
{
static void Main()
{
var myClassInstance = new MyOtherClass();
myClassInstance.DoSomething();
}
}
}

namespace MyNamespace.Utilities
{
class MyOtherClass
{
public void DoSomething()
{
Console.WriteLine("Doing something...");
}
}
}