Question

Is there any way to import classes and other files in c# like “include” in PHP ?

Answer 1

There is no include in C#. The closest you can get is creating classes that reside in namespaces, then generate a using for that namespace.

For example, say you create a class in a separate file of your project and assign it to a namespace:

namespace ProjectNamespace.SecondNamespace 
{
    public static class HelloWorld 
    {
        public static string Greet { get { return "Hello, World!"; } }
    }
}

Now, in your main project, you can reference that namespace in two ways. Let’s assume your main project files look something like this:

namespace ProjectNamespace
{
    public class WhatWeDo
    {
        public void WeGreetTheWorld()
        {
            // Here, we greet the world
        }
    }
}

Now, to put our HelloWorld class into the above code, we can either reference it directly, or add a using to the top of the page. For fully referenced method, substitute the comment above for:

public void WeGreetTheWorld()
{
    string greeting = ProjectNamespace.SecondNamespace.HelloWorld.Greet;
}

Or, we can add using ProjectNamespace.SecondNamespace to the top of the file, then just reference the class directly.

using ProjectNamespace.SecondNamespace;

namespace ProjectNamespace
{
    public class WhatWeDo
    {
         public void We GreetTheWorld()
         {
             string greeting = HelloWorld.Greet;
         }
    }
}