Active Oldest Votes. Improve this answer. Mark Lalor 7, 17 17 gold badges 64 64 silver badges bronze badges. Well, maybe my example is not so good. I wish to be able to call my extra code, with all my variables. Importing the module doesn't help me much as I would need to transfer the variables, no?
Variables can be imported as well, although it's not very common and you typically don't want to do that Here is how I would rewrite the main program f1. Hello, World! Display class property myVar: 9 Display global variable gMyVar: 10 I think the point to Markus would be: To reuse a module's code more than once, put your module's code into functions or classes, To reuse variables stored as properties in modules, initialize properties within a class and add "getter" and "setter" methods so variables do not have to be copied into the main program, To reuse variables stored in modules, initialize the variables and use getter and setter functions.
The setter functions would declare the variables as global. Ali Afshar Ali Afshar You would be better off organizing your code into modules Example: F1.
Carl Groner Carl Groner 3, 1 1 gold badge 16 16 silver badges 20 20 bronze badges. Can I change it somehow? If you're using precompiled headers, there's less IO. I haven't measured it, but I would say compilation of a single file still takes much longer than just reading the file, at least on SSD. No - depending on what kind of optimisation level you chose, compilers are CPU bound just as often. He had to return to 'drawing board' and rewrite parts of the compiler so that it was able to compile programs on any computer.
Then came to be 'make' which allowed to split the program on pieces and recompile only parts affected by change. It started new evolution of the code. Show 1 more comment. The other answers are fine, but something they're missing is actual technical limitations. Telastyn Telastyn k 29 29 gold badges silver badges bronze badges. Most filesystems can hold files multiple TB large — Qwertie. Editor and compiler constraints are probably going the kick in way before file system limits, so that might be a better lead — Morgen.
Add a comment. Also does a multifile application ACTUALLY run faster than a singlefile one In C, there is no reason to assume that a multi-source-file application will run faster, and several reasons why it might be slightly slower.
Community Bot 1. The only answer to actually answer the question. DocBrown No, that sentence was too broad and "listy" so I ignored it. Advantages of using multiple files for a program are numerous. For instance: if you write code for a class in a separate file, you can use that class in multiple programs. It increases reusability of the code.
Furthermore, if you want to change anything in a class, you will only have to change it in that particularly file and the change will be automatically reflected in all the projects referring to this file.
Furthermore, it is advisable to write large complex programs in multiple smaller files. And last but not the least, in large organizations, several programmers are working on a project.
In such scenarios, each programmer is responsible for designing designated modules; therefore separate files for each programmer, are convenient to code and then subsequently integrate. Christophe This is the oldest answer and seems very relevant. I have added some line separators to facilitate reading, and replaced "document" with "file" for the consistency of the terminology. It would help if you could develop the 3rd bullet.
You could also add that in many languages, separate files can be compiled separately, so that only the changed files are recompiled. The first 2 are not necessarily true. If you have multiple classes defined in your single file program, you can still import it later in another project. The question is asking why 3 is true Another significant reason to use multiple files that somehow no one has mentioned: When you work on a software development project with a team, it is very common to use a version control system such as Git.
What is git please? Asadefa Git is a version control system for tracking changes to your code. It maintains a history of all edits that any person has made to the code, and additionally has features to automatically merge changes together when possible.
It is an industry standard for managing code in software projects, and something you'll probably need to learn if you want to be a professional programmer. See git-scm. That is a reason to use a commit-hook forcing autoformatting with the one true style.
Sally or Tom could reconcile it by adding manual runs of the autoformatter without too much extra-work anyway. Still not nice. Deduplicator Yes, I oversimplified for the sake of example. As long as nobody reorders stuff, the conflicts with the one big file are exactly the same as with the many small files.
You only get increased risk of merge conflicts when one of the authors reorders some functions in the huge file. However, those conflicts may turn out to be next to impossible to sort out, so it's definitely a good-enough reason to use many files. Cap Barracudas Cap Barracudas 5 5 silver badges 14 14 bronze badges.
Hopefully I've explained why and how to split up your code into multiple parts without bringing in "classes". They're a great idea and are just the thing for games and Java's a great language for OOP. But it's better to know why you're doing what you're doing. Leave OOP alone until it starts to make some sense to you.
One of the benefits is re-usability. A program is basically a bunch instructions grouped together. You'd find that some of those instructions are suitable for other programs as well. Let's say you make a jumping game. Later on when you decide to make a cannon game, you find that the physics calculation you used in the jumping game comes handy here. So instead of writing it again, or worse copy and pasting it into the new program, you make it into a class. So next time you make another game where the game mechanics requires physics, you could just reuse it.
Of course this is oversimplified but I hope it makes sense. Please correct me if I make some incorrect assumptions about how classes work in Java. Classes are primarily useful when they are instantiated. A class of which no instances are created really is really just a glorified namespace. If you use all your classes this way, then indeed, the benefits of moving things from namespace to namespace may seem insignificant -- at most, you'll win by having some private data in each and thereby encapsulate things a little.
However, this isn't where classes shine. Consider the String class: you could have all the same features using char arrays and some static functions. At this point, functions give you a little extra safety and syntactic sugar. You can write string. Moreover, you know that if someone gave you a String , it was created with the String constructor and that it must work with the length function -- if the array version can't handle some character then it has no way of preventing you from putting it in there.
That's still not it, though. The key point is that classes bundle data and functions that operate on it and abstract both of it away. When you have a method void f Builder b you know you'll be getting a Builder , and you can expect that it will support certain behaviour.
However, you know nothing of data or the functions being executed -- in fact, the definitions for both may not be written yet as you write and compile f. The first point to understand is thus that classes make it convenient to pass around data while making sure it is not broken. The second point is that both what data and what function implementations an object has is something about the object, not something you can just tell from its type.
The whole idea is based on a general rule named divide and conquer. This paradigm can be used almost every where; you divide a problem into smaller problems and then you solve these little, simple and well-known problems. Dividing your program into classes is one of the types of division which started to become common in last decade.
In this programming paradigm we model our problem by some objects and try to solve the problem by sending messages between these objects. Some people might say that this approach is easier to comprehend, expand and debug. Although some people disagree :. It is not about splitting a program into classes but about how you model your application i. Splitting things is just a mechanism we use to understand complex things better. It is not only with programming. Imagine circuit board with many wires entangled with each other, forming a complex structure with each wire connecting somewhere spaghetti code.
You'll have to follow each wire to its end to figure out the connections. On the contrary imagine wires that are grouped and color coded as per their function. It becomes a lot easier to fix things. Idea is that you don't start with a long program and then split it into classes. Sign up to join this community. The best answers are voted up and rise to the top.
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