Subtitles of the Movie

Let's start our course with a discussion of application programming. First, let's take a look at a very common and very simple desktop application program, and by the way, I am running Microsoft Windows 2000 Advanced Server Edition, that's the operating system that we are going to be using for all our Visual Studio .NET work. So if you are on a computer as well, let's go to start, programs, accessories, and let's see, how about the calculator? Here's Microsoft's popular and very simple calculator accessory, notice it has an area for input, we could put numbers in and we can get an output, the answer. This is a common feature of all computer programs, input goes in, outputs come out. Okay, let's close the calculator, and let's talk just for a second about desktop application programs. Application programs are written using any of a variety of programming languages, the programming language is then compiled into the actual executable program file, which is usually a file with the .exe as the extension of the file name. These programs are compiled so that they will run on a particular operating system running on a particular set of hardware. So they're not easily transportable, as a matter of fact if you want to make one of your existing programs work on a different operating system or different hardware, you generally have to port it, which means rewriting the source code and recompiling. So what is the process used to write an application? You might start by making some specifications. Let's open up WordPad, then we might write something like calculator program, specifications, we might specify the size, the speed, the reliability of the program, the security and features and that gives you a general idea of what our specifications might be. So your next question might be well, what process do we use to actually write the code, do the construction development work that creates the program? Most programs can be written very simply, you can use something like Notepad and any kind of text editor to write a program. For example, I will write a simple web page right now, using Notepad, if you've ever done any HTML work, you know how easy this is to do. Now I have written my simple web page and all I have to do is save it to my desktop, I will save this as hi.htm Just change this to all files, now I have hi.htm on my desktop, I double click it, it opens up in Internet Explorer by default, there's my web page, obviously this isn't much of an application, but it gives you an idea of how most programs and markup language documents are written. So now it should be clear that you can write application programs using nothing more than a text editor. They have to have some tools, you have to have a compiler if you are writing a desktop application program, because it has to be compiled before it can run. If you are writing web pages, obviously you can write them very quickly and easily using nothing more than a text editor, as for compiling, you can include JavaScript which is a programming language for web pages, it operates in the browser, in the user's browser, it doesn't need compiling so you can write the code right inside your HTML. If you're writing a desktop application program, you can write the code using Notepad, but there's other tools that make the job much easier and the fancier tools are actually automated development tools. A good example of an application programming tool is Microsoft Visual Studio .NET, let's go ahead and open it up, go to start, programs, Microsoft Visual Studio .NET, Microsoft Visual Studio .NET, and here it is, not much there and you are on the top, toolbars, but in this program, there are a number of code editors, templates and debugging facilities that help you rapidly develop your applications, in fact, there's even a name for this process it's called rapid application development or RAD, Now as an application program, a desktop application program, Visual Studio .NET is also called an integrated development environment. That means that it has all the tools, templates, features, connections and so forth, to integrate the development process all into one application program.