Newbie confusion to do with Main() when trying to tidy up a program.

Question

This is a general problem I have always had trying to understand how C# is meant to be used. It might be that there is some silly syntax mistake I always make, so I think I can't do something, or it could be failure to get it at all.

I write a program to do something. It has a few classes with their variables and methods etc and it has one class which contains Main(). Pretty much the only thing in that class is Main().

I develop the program to do what ever it is meant to do and eventually I get it to work. When I've finished Main() might be a few hundred lines long and has a whole bunch of variables and some code controlling instantiations of classes.

And that is all fine except I don't like the look of the long piece of code in Main(). It is too big to follow easily and maybe has a couple of big nested loops etc. Additionally I might decide that now its working I'd like to loop through the whole thing with different options or whatever.

So, I want to take some of the bigger chunks of code in Main() which have specific purposes and turn them into new methods. That way the code will by much easier to understand and adjust.

And this is where it goes wrong for me, I can't seem to work out how, in general, you are meant to partition the Main() method into several new methods.

* You can't define methods at all within Main(), it seems that just isn't allowed - or am I wrong????

* If you put the new methods into an existing class, the class needs access to all the variables and methods previously in Main() i.e. it needs to contain them. It might be the case that sometimes this makes sense but in general it is probably no good because they don't really belong there and also Main() then has to access them through the class instance.

* You could put the data and new methods into another new class. This would be like a program flow control class. But does anyone do that? It just seems clunky. And main still has to access them through the class instance. It just strikes me that I am moving all the stuff I expect to find in Main() into another class, just so that I can make some local methods. In the end Main() won't have any purpose other to instantiate and run the other class. This just can't be what was intended - or is it????

* You can put the data and new methods into the class which contains Main(). But this is really just a special case of the previous option, the data might be in the same class as Main() but it still has to be accessed through a class instantiation.

Have I missed some basic point or what?

Thanks in advance.

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I'm having to reply here because "reply" doesn't seem to work for me...

Thanks so much for your response. I feel a lot better about it now. I have several books in fact, I don't know if they are good or not but I think they are acceptable. What has caused me the confusion is that the books are restricted to smallish programs and so the reader never sees my problem arising, everything can go into Main() and that's just dandy. But when I go on a spree and Main() gets over a certain size, I just begin to think, hang on, this can't be right.

The last program I did was a nightmare to partition. After reading the reply below I think the mistake I make when I know a program might get big, is declaring all the variables inside Main() at the start. If they were declared inside the Program class to begin with then accessibly issues would get sorted out as the program developed, where as moving them out of Main() later is always as disaster.

After posting I did wonder about Main() being the method called at runtime and so perhaps it really was meant to just call up another class (unlike the book examples!). I haven't had to integrate with other C# code yet but I imagine this must be easier if Main has as little in it as possible.

In fact I expect this is the correct way to think about it. Rather than treat the code as a big program which does such and such, treat it as a piece of code that might just sit around in a class in a namespace and perhaps get called once in a while. From that point of view then, all the program flow control stuff is clearly just a regular method inside just another class. And Main() has nothing to do with it. Then I just use main to make an instance of my code being used.

But what actually happens is that when a program is fairly small or is going to get deleted anyway, people are bound to think it isn't worth the trouble of writing the code in yet another method. So all the examples you get as a newbie fail to make this clear.

Sam Hobbs · Answer

Yes there is a fundamental point that has critical relevance here. The Main function is what is executed by Windows (it is often called the entry point); at least indirectly through .Net. The Main function must be called in a manner that works for all languages; it cannnot be dependent on features of C#. So Main does have some special requirements. So you have two general solutions. First note that in the code generated by Visual Studio for console applications the class that Main is in is called Program. The Program class is static. When you learn more about what that means you will be better able to understand why the Program class (whatever class containng the entry point is) must be static. You can add members to that class but the members must be static. So you can add functions to the class (outside the Main function) but they must be static and the functions can use static objects in the class. Or you can make a new class and create an instance of it in Main and then call a function in that class. Note that you will usually have only one instance of that class so it does not accomplish much to create a non-static class. To theoretically justify the option of creating another class (in other words to make you feel better about it) just look at it this way. You can use the Main function as an interface (interface being a general term not as defined by C#) between Windows and your C# program. Yes you definitely should make the code more logical than putting it all into the Main. This will all make more sense and easier when you become familiar with the fundamentals. Please get a good book about C#.