Is it possible for a program to open up a text file and use it as c++ code? If so, how? What if a program wanted to append code from a text file to itself? Can that happen?
Thanks!
Depends on what you mean by "text file" and "use it as c++ code." If by "text file" you mean a file containing uncompiled C++ code, and by "use it as C++ code" you mean execute it, the answer is no, you'd need to compile it first before it's of any real use (unless you want to write some sort of interpreter or compiler).
With regards to your second question, I suppose it's possible, but it'd be really hard because you would need to compile the C++ code in that text file into binary, then insert it into the program in a meaningful way.
If you're doing this just for curiosity, you might have better luck with an interpreted language (such as Perl or Ruby). I was a bit curious myself, so I took a stab at the problem with the following ruby script (saved in alpha.rb):
File.open('alpha.rb', 'a') do |file1|
file1.puts "\nprint 'Sneaky Addition!'";
end
After you run it, you'll see that a new line of code has been added. If you run it a second time, it'll run the code. I believe the reason that it isn't run the first time is that the file is already loaded into Ruby when it's run, so it doesn't see the change to the file until it reloads it.
Of course, we could possibly get around this by using a second file (as explained here)...
Alpha.rb
print "Alpha running...\n"
File.open('beta.rb', 'a') do |beta|
beta.puts("\nprint \"But alpha got the last word.\\n\"")
end
load 'beta.rb';
Beta.rb
print "Beta running...\n"
File.open('alpha.rb', 'w') do |alpha|
alpha.puts("print \"Sneaky Beta addition.\\n\"")
alpha.puts("\nprint \"Beta overwrote alpha!\\n\"")
alpha.puts("\nprint \"This code only works once =) \\n\"")
end
load 'alpha.rb'
I suppose you might be able to do something similar in C++, but it'd be much more complicated since you would be compiling your code into binary, and even then you probably can't just append it.
Related
Things that i should note are that I am using the latest version of vs code to write in c, my compiler is mingw-w64. Whenever I run a simple code (Hello world for example) everything works then suddendly when I try to do something else a message appears saying (program name).exe was not found. This generally happens when I try to use commands from other libraries, i tries using conio.h textcolor() but it doesn't want to, but when i use getch() it works fine. Moreover the .exe file exists, then i add a single line of code and boom suddendly it doesn't exist. Can anyone explain to me what is going on??
For a class assignment we needed to write a compiler. This includes an optimizer portion. In other words, we take in a file with some "code". An output file is generated. In the second step we take in the outputted code and remove any "dead" code and re-output to a second file. I have some problems with the optimizer portion and would like to use gdb. But I can't get gdb to operate properly with the input and output files arguments. The way we would normally run the optimizer is:
./optimize <tinyL.out> optimized.out
where tinyL.out is the file outputted in the first step and optimized.out is the file I want to output with the new optimized and compiled code.
I have searched Google for the solution and the tips I have found do not seem to work for my situation. Most people seem to want to only accept an input file and not output a separate file as I need to do.
Any help is appreciated (of course)
I'm not exactly sure what you're asking. But since I'm not yet able to comment everywhere, I write this answer with a guess and edit/delete if necessary.
When GDB is started and before you start the program you wish to debug, set the arguments you want to use with set args.
A reference to the documentation.
You just need to do the file redirection within gdb.
gdb ./optimize
(gdb) run < tinyL.out > optimized.out
https://stackoverflow.com/a/2388594/5657035
I am having trouble with the function fopen(). I would always send the exact location of a file as an arguement to fopen(),
which would look something like this:
fopen("c:\\Users/Username/Desktop/Projects/program_name/version 1.0/data/important_data.txt", "r");
That works just fine on my computer, but what if I decide to transfer the program to another computer?
The location would completely change.
It would no longer be:
c:\\Users/Username/Desktop/Projects/program_name/version 1.0/data/important_data.txt
But it would rather be something like:
c:\\Users/OtherUsername/Desktop/program_name/version 1.0/data/important_data.txt
My question is, how do I make a portable function which can obtain the location of a file, if I only give the
name (including the type e.g. .txt) of the file to the function?
Keep in mind, I've been learning C for less than a year. There are still a lot of things which I must learn, and
things like this are of high importance.
this is operating system specific. on linux you can use the locate shell command and parse its output ( http://www.linfo.org/locate.html )
C: Run a System Command and Get Output?
How do I execute a Shell built-in command with a C function?
however this solution will only work on linux. i think yano's solution in the comments above is better ...
i'm trying to do some code in a keyboard driver, a 3rd party software that looks like this can run the command i'm trying to do in a plugin file that compiles alongside the daemon that the command needs to be sent to. the command looks like this.
g15_send_cmd (g15screen_fd,G15DAEMON_MKEYLEDS,mled_state);
here's the code i'm working with and trying to run the command in (it compiles as a plugin with the daemon. in the uncompiled source it's
"g15daemon/plugin/g15_plugin_uinput.c"
the file that defines the command is in
(link)
"g15daemon/libg15daemon_client/g15daemon_clinet.h"
whereas with the g15macro (3rd software) is run from outside the daemon for various reasons i don't want to (and pretty much can't) use it, one being speed of execution of commands when keys are pressed.
so the program compiles like this without error it seems. but if the code i specified above activates, the driver(daemon) crashes giving
g15daemon: symbol lookup error:
/usr/lib/g15daemon/1.9.5.3/plugins/g15plugin_uinput.so: undefined
symbol: g15_send_cmd
what did i do wrong or what am i missing here? (and i'm sorry if the code in the plugin file is ugly down by that switch command, but i didn't know how to do any better since i don't know C much at all, all i have behind me are Py and C#)
Edit: the solution was given
but i don't know how to add a linker flag, also since it links to a part of the program being compiled will it even work?
You forgot to link your plugin with g15daemon_client library. The simple way to fix it is to add -lg15daemon_client to the linker flags.
I have a huge project, whole written in C language and I have a single make file that is used to compile it. The project C files contains lots of capitalize problems in it's header files, meaning there are tones of header files that were miss-spelled in lots of C files.
The problem is I need to migrate this project to compile on Linux machine and since Linux is case sensitive I got tones of errors.
Is there an elegant way which I can run make file in Linux and tell him to ignore case sensitive?
Any other solution will be welcome as well.
Thanks a lot.
Motti.
You'll have to fix everything by hand and rename every file or fix every place with #include. Even if you have a huge project (comparable with linux kernel), it should be possible to do this during a hour or two. Automation may be possible, but manual way should be better - because script won't be able to guess which name is right - filename, or the name used in #include.
Besides, this situation is a fault of original project developer. If he/she wasn't sloppy and named every header in every #include correctly, this wouldn't happen. Technically, this is a code problem similar to syntax error. The only right way to deal with it is to fix it.
I think it takes not too long to write a small script, which goes thru the directories first, then replaces C headers. Explained:
Scan the headers' folder and collect filenames.
Make a lowercase list of them. You have now original and locased pairs.
Scan the C source files and find each line contains "#include"
Lowercase it.
Find the lowercase filename in the list collected and lowercased from headers.
Replace the source line with the one collected from headers.
You should put the modified files into a separate folder structure, avoid overwriting the whole source with some buggy stuff. Don't forget to create target folders during the source tree scan.
I recommend a script language for that task, I prefer PHP, but just it's the only server-side script language which I know. Yep, it will run for a while, but only once.
(I bet that you will have other difficulties with that project, this problem is not a typical indicator of high quality work.)
Well I can only tell you that you need to change the case of those header files. I don't know that there is any way you can make it automatic but still you can use cscope to do it in a easier way.
http://www.linux-tutorial.info/modules.php?name=ManPage&sec=1&manpage=cscope
You can mount the files on a case-insensitive file system. FAT comes to mind. ntfs-3g does not appear to support this.
I use the find all and replace all functionality of Source Insight when i have to do complete replacement. But your problem seems quite big, but you can try the option to replace every header file name in all occurences of source files using the
"Find All" + "Replace" functionality. You can use notepad++ too for doing the same.
A long time ago there was a great tool under MPW (Macintosh Programmer's Workshop) called Canon. It was used to canonize text files, i.e. make all symbols found in a given refernce list have have the same usage of upper/lower case. This tool would be ideal for a task like this - I wonder if anything similar exists under Linux ?