Okay. As promised in the last segment, we're in my directory. My prompt for my computer is Iras-Air: and the local directory that I'm running in is called CPrograms/W1. So here's where I develop some of the code that was being used in Week 1 of this class. So let's look at that directory, the way we can see that directory again where in terminal, for a Mackintosh terminal window, which is basically running Unix. So I can use Unix commands, the Unix command LS shows me the files in that directory. So we see there's an a.out file, there's something called add2.exe and then there are these.C files which are source files which are code and there we can see something like miles.exe, circle.exe, add2.exe. So all of that are what I previously compiled as N2 and executable and I can of course execute them. Let's look at add2.exe. So in order to execute them, all I have to do is say add2.exe, it says input two floats. I do that and I'm done, 4.3 and 6.8 is 11.1. Now, if I want to develop a program, let's say I want to change the input to floats program to an input three floats. Let me try doing that. So I'm going to have add3. I'm going to call it add3.c., vi add3.c. So this command means create a file called add3.c. Now, it's going to look very much like add2.c. So basically and frequently the cases, I'm going to want to modify a pre-existing file. So I'll just read that file in and these are all VI commands. Again, in this class, I'm not going to go through all of the VI commands or Notepad commands, you're just going to have to get comfortable with using an editor. Netter is a critical tool for almost anything on a computer. Once you understand a little of it, you can get a tutorial that explains in detail the editing commands you need. I miss titled that file so I couldn't read it. There it is, Read in Two Floats. So here's a classic thing, let's change it to three. So that was a CW that I printed and that means change word and I'm going to change the word to three. Today is not the 18th, it's the 19th. I'll change that. Again, I might have a sample program of some kind and there's always going to probably have include standard I hope. So I don't have to always be redoing my program. I have something standard. Now indeed if you go to an environment and windows with something like an IDE, more elaborate IDE, like visual studios, it'll probably give you a basic template for starting such a program. So an integrated development environment like visual studios, once you get the hang of it though, the sketch so much stuff in it that that can be intimidating. Does give you a leg up on doing programs, gives you a lot of additional assistance. So instead of float a, b, we need a third. I'm going to just do an addition here. So I'm going to also have a c,. Okay. So little a says add at this place, it's a way to do an insert. Here I'm going to say input three floats, and I'm going to make an error here, because I want to show you the whole cycle. So let's make an error. I'll hit the wrong code side. So many places in a C program, we have to have matching braces, parentheses, all sorts of things have to match. Here I'm going to get third float. I'm going to print the third float. I'm going to do an insert that's another way to add immediately. So that'll be c equals percent f. Here I'm going to also make a mistake. I'm not going to put C in it. So it's expecting three values but it's only going to display two values. What's going to happen there? Again we're going to see how the compile edit cycle works. So I'm done now and I can exit and I can do a colon. I can do a colon quit. I can try to compile now. So I'm ready for the next phase which is to call the compiler. I'm going to use this dot o just say that I want that to be add3.exe if it works and add3.c is my file to compile. Whoops warning. Missing terminal quote invalid and it even shows it. This is not being matched. So that's pretty good. Then it says error makes a number of other errors because there's confusion about matching. So let me re-enter that editor. I use a shortcut I just said!V which means I use the previous editor command. Let's go and correct this error. It pointed it and even told me what line it was on. So I'm going to try and redo this and I'm going to go ahead and also- okay, one warning and two errors generated. It said a warning. There was more conversions than arguments. That's not a syntax error and it's say something where your compiler is intelligent enough to show that something did not make sense but the warning didn't allow me, I believe, to still go ahead and build an executable. This says input three flows, 3, 4.5, 6.6. Look what happened here, I got 3, 4.5 but C was shown as 0, but the right result happens, 6.6 and we ended up with the sum of 14.1. So if we fixed the program based on that warning and I'm going to go back and do that, we wouldn't have get that funky C equals zero because C equals zero was the initialized value of this float, but it was changed by the scan F but it didn't show up in the print F because here it said percent F and there was nothing to read out of. So here we're going to now correct that. Think I corrected it and we recompile. No warnings. No errors. Everything looks okay. Let's try the add3. Input three floats 1.1, 2.2, 3.3. That should be what, 6.6, I hope. Sure enough. Done. So we've seen how we get syntax errors, how the compile cycle works, how we run recompile, make our fixes and finally get working executable. Indeed if we go and look in the directory, there's add3.exe and our program. So this is my working environment may not be yours. You might have a different Unix. This is under the Mackintosh. But mostly Unix environments will look like this, where you might have a totally different environment for Windows and you'll have to use a different editor and probably a different compiler or you can import a new compiler within Windows and use a Windows Terminal box as well, if you want to approximate this environment or you can again go and use Visual Studios and use one of its simpler Project moves and get you here.
