I'm fairly new to C++ and I want to make a Program Launcher, All it does is launch applications for me based on text I input.
I all ready have the basic code for it, but I can't seem to find out how to change the working directory. I know you use chdir, but how Exactly.
C++ still has very little standardized support for filesystem functions, in part because it runs on embedded devices which may not have working directories, or sometimes even directories or files at all. So we have to look to the OS API.
For POSIX, there is chdir() and getcwd().
For Windows, there is SetCurrentDirectory and GetCurrentDirectory, although if you want to deal with per-drive working directory, you will need to work with environment variables.
There is an example on MSDN titled Changing the Current Directory
Related
I've got a makefile (a file called 'Makefile' which is run by cmake in Linux, but works in Windows via nmake I believe and needs to be run in VS command prompt.)
And most of the 'sample' ones I can see are just one line (and the rest appear to be stuff I don't 'yet' understand and then this same one line.
include $(shell rospack find mk)/cmake.mk
(in the terminal rospack find [package] returns the path to said package, and cmake.mk is obviously the file it wants to include)
My problem is, that this appears (to me at least) to be written for use in a Linux system (which basically the entirety of ros, the program I'm working with, was) and in Windows this appears to just try to be
include /cmake.mk
(which unsurprisingly doesn't work)
Basically I need to know how to do the same thing in windows, generally in a 'dynamic' way, as it will only cause more problems down the line if I get this working by hard-coding the directory path and then it breaks because its not set properly some time in the future)
So I guess if this isn't possible or is particularly hard, a way of hard coding it would be a stopgap.
I tried:
include C:\[directory]\cmake.mk
but it seems to have issues with the ':'
I'm trying to work with Windows, because later in my project I'll be needing to use another program (for i90 robot) for which we only have Windows support.
OK, so apparently it acts differently if the file is actually in the folder.
as in
include C:\[directory]\cmake.mk
Errors with
C:\[directory]\cmake.mk not found
if the file isn't there, and
fatal error U1034: syntax error : separator missing
if it is
While this doesn't really seem to impact on the original problem, I guess it indicates I'm trying to do something funky windows doesn't like.
The short answer is, you'll never get a single makefile that does much of anything complicated that will work both with standard UNIX-style make (such as GNU make from GNU/Linux) and also work with nmake. Nmake is a completely different beast.
As an aside, it's confusing that your makefiles here are called "cmake", because cmake is an actual program, distinct from make (and nmake). I'm assuming, though, from the context that the use of the term "cmake" here doesn't refer to the actual cmake utility. Which is too bad, because if it did use cmake things would be simpler for you. Maybe.
It's not clear exactly what your requirement to use nmake is, though. If you laid out your real requirements, it would be a lot easier for us to advise you. For example, you say you need to use a "another program" which runs only on Windows. What does this program do, exactly, and how will you need to use it? Does it provide libraries that need to be linked with the "ros" code?
Basically, your simplest way forward is to obtain a UNIX-like environment, including tools like GNU make, for your Windows system. There are two main choices: Cygwin, which provides a completely POSIX infrastructure including shell, compiler, etc. which are ports of the GNU environment to Windows but require a POSIX layer, and MinGW, which has various GNU tools that run more or less natively on Windows.
However, if you MUST use Visual Studio as your compiler, for example, then these will be much more difficult to integrate.
I've heard that you can take a program that is already installed in a PC and go home to you r own pc and write a program in any programming language to make it work without having to install the program. I wanted to know how does one go about in achieving that.
The class of applications you are describing are called Standalone or Portable Applications.
In such applications all files that are required to run the application are stored in the same directory as the application file itself. Which is not the way with most applications work, so, you cannot make all applications run in that fashion. There are various guides on Google when you search for 'creating portable applications'.
You might want to look at a good directory of portable applications here
For a university course I have to write a http server which is supposed to run on both Linux and Windows.
I have got a humble Linux machine which I don't think can handle any kind of heavy virtual environment, neither I'm willing to go through the hassle of installing it.
This is the first project of mine complex enough (I estimate ~1.5 months to develop) to require an environment sufficiently comfortable to alternate rapidly between short coding and testing sessions (the latter on both platforms, of course).
So, I was wondering what could be the best set up for this situation. I think testing it on Wine would be ok (it is not a real-world thing, after all), and I installed MinGW for the Windows-targeting part.
Basically, a simple well-written makefile could solve my problem... It should build both the Linux and Windows binaries and place them in the respective folders (the Windows one in the Wine sub-tree) and I'm all done! But I feel very inexperienced in this thing and I really don't know where to start. Maybe the make manual, ahah!:)
Thoughts, suggestions, anything I didn't think/know!
Thank you!
(PS. I'm planning to use emacs as editor, or maybe learn vim. Unless eclipse provide some kind of skynet-like plugin that entirely solve this problem...:)
You're on the right track. It's not that complicated, really, thanks to MinGW. You basically need two things:
The code has to be portable across the OSes. MinGW has some POSIX support, but you'll probably need to either use Cygwin in order to be able to use the POSIX interface or have your own compatibility layer for interfacing with the OS. I'd probably go for Cygwin as then you can code only against POSIX and won't have to test and debug your compatibility layer. Also, make sure you won't use any external libraries that are OS specific. Non-portable code often results in a compile error, but make sure you test the application thoroughly anyway.
The toolchains for targeting Linux and Windows. You already have them, you just need to use them correctly. Normally you'd use a variable like $(CROSS_COMPILE) as a prefix when calling the toolchain during cross compilation. So when compiling for Linux, you call gcc, ld, etc. (having the CROSS_COMPILE variable empty), and when compiling for Windows you call e.g. i486-mingw32-gcc, i486-mingw32-ld etc., i.e. CROSS_COMPILE=i486-mingw32-. Or just just define CC, LD etc. depending on the target.
I wrote a small game on Linux and made it run on Windows as well. If you browse the code, you can see the code has next to no #ifdef jungle (basically just some extra debugging features enabled for Linux), and the Makefile is simple as well, with no complicated handling for cross-compilation, just the possibility to override CC etc. like it should be. As lots of important open source software is written this way (especially software that's used by the desktop and embedded devices), you should also be able to find lots of other examples on how to set up the build environment correctly.
As for testing the application on Windows, I think the best option is if you can find a real Windows machine somehow. If you do everything correctly, it should run the same as on Linux and you won't need to continuously test your application on both OSes. If testing on a Windows machine is not possible, a VM would be the next best choice, though it would probably be more difficult to set it up. Wine is a good backup plan, but I don't think you can be sure your application works well on Windows if you only tested it on Wine.
is there a way to compile Erlang to be a stand-alone executable?
this means, to run it as an exe without the Erlang runtime.
While it's possible to wrap everything up in a single EXE, you're not going to get away from having an Erlang runtime. Dynamic languages like Erlang can't really be compiled to native x86 code, for instance, due to their nature. There has to be an interpreter in there somewhere.
It's possible to come up with a scheme that bundles the interpreter and all the BEAM files into a single EXE you can double-click and run directly, but that's probably more work than you were wanting to go to. I've seen it done before, but there's rarely a good reason to do it, so I won't bother going into detail on the techniques here.
Instead, I suggest you use the same technique they use for Python's py2exe and py2app programs for creating Windows and Mac OS X executables, respectively. These programs load the program's main module up into a Python interpreter, figure out which other modules it needs using the language's built-in reflection mechanisms, then write out all those compiled modules along with a copy of the language interpreter and a small wrapper program that launches the program's main module with the interpreter. The directory containing those files is then a stand-alone environment, having everything needed to run the program. The only difference in the Erlang case is that python.exe becomes erl.exe, and *.pyc becomes *.beam. The basic idea is still the same.
You can simplify this if you don't need it to work with any arbitrary Erlang program, but only yours. In that case, you just copy the Erlang interpreter and all the .beam files that make up your program into a single directory. You can make this part of your program's Makefile, for instance.
You can then use your favorite setup.exe or MSI creation method for creating a distributable package that installs this collection of files into c:\Program Files\MyProgram on the end user's system and creates a shortcut for "erl mainmodule.beam" in their Start menu. The end user doesn't care that as part of the program they also get a copy of Erlang. That's an implementation detail.
you can use Warp. I've added examples for wrapping an Erlang release.
Simple question here (though perhaps not such a simple answer):
Is it possible to specify a path for an (existing) named pipe that can be used by programs as if they were opening on a normal file?
According to this MSDN page, name pipes on the local computer can be referrenced using the following path syntax: \\.\pipe\PipeName, yet I'm having no luck using this from standard Windows programs.
As a side point, if anyone has any suggestions for interfacing with programs that are only capable of using the file-system in a more efficient manner than physical I/O (e.g. named pipes), I would be glad to take them.
It would only work if the programs are using the Win32 API CreateFile() function to open the files.