create extern to be usable in c#

Create extern to be usable in c#

When it comes to programming in C#, you may want to use external functions or variables that were not defined within your own code. In this case, you would need to create an "extern" declaration.

The "extern" keyword is used to declare a method, field or property that is implemented externally to your code. This tells the compiler not to look for an implementation in your code but to look for it elsewhere.

Creating an extern method

To create an extern method, you would need to declare it using the following syntax:

public class ExampleClass 
{
    [DllImport("ExternalDLL.dll")]
    public static extern int ExternalMethod(int arg1, int arg2);
}

In the above example, we are declaring an extern method called "ExternalMethod", which takes two integer arguments and returns an integer. We are also specifying that the implementation of this method can be found in an external DLL called "ExternalDLL.dll".

It's important to note that in order to use the "DllImport" attribute, you would need to include the System.Runtime.InteropServices namespace at the top of your code file.

Creating an extern variable

To create an extern variable, you would need to declare it using the following syntax:

public class ExampleClass 
{
    [DllImport("ExternalDLL.dll")]
    public static extern int ExternalVariable;
}

In the above example, we are declaring an extern variable called "ExternalVariable" that is of type integer. We are also specifying that the implementation of this variable can be found in an external DLL called "ExternalDLL.dll".

Using externs in your code

Once you have declared your externs, you can use them in your code just like any other method or variable. For example, you could call the ExternalMethod we declared earlier like this:

int result = ExampleClass.ExternalMethod(5, 10);

This would execute the "ExternalMethod" function with the arguments "5" and "10" and store the result in the "result" variable.

Conclusion

The "extern" keyword is a powerful tool that allows you to use external functions, variables, and other resources in your C# code. By declaring externs and specifying where their implementation can be found, you can easily incorporate external functionality into your own applications.