how to test C or C++ snippet quickly? - c++

I am using Ubuntu and Eclipse as an IDE for C/C++.
I currently have a big project in Eclipse. Sometimes, I want to test some small functions written in C/C++ but I don't want to re-create a new project in Eclipse. It is much time consuming and slow. I want to ask if there is any better way to do this ?
(In the past, I usually used a combination of GEDIT and GCC from the shell, but I really like the auto-completion or intellisense feature in Eclipse, which GEDIT does not have. I have also tried Scribes but it does not have a full intellisense feature like Eclipse)

Use online compiler like Ideone or Codepad.
Ofcourse, they dont provide you auto code completion feature & other fancy features but that is the price you pay for quick & easy way of checking stand alone functions.

This method works without an internet connection and without exposing your code.
<ctrl>+<alt>+T <-- 0) opens a terminal
vi test.cc <-- 1) hackery
...
g++ -Wall -Wextra test.cc && ./a.out <-- 2) compile + run
rm test.cc <-- 3) clean up (optional)
Replace vi with your favourite editor or cat. Can't be less obtrusive.
Some editors like SciTE have some very basic code completion (btw btw: SciTE has shortcuts to directly compile and run code from within the editor).
Btw: QtCreator gives some decent "intellisense", and the project files are minimal. A single project file line is enough for such one-function-test.
unkulunkulu points out that you can also replace step 2 like this (there should better be no Makefile in your try-out folder; could conflict with existing targets in that):
<ctrl>+<alt>+T <-- 0) opens a terminal
vi test.cc <-- 1) hackery
...
make test && test <-- 2) compile + run
rm test.cc <-- 3) clean up (optional)
It has the tiny disadvantage that telling g++ about extra arguments (like -Wall or -std=c++0x is a bit more obtrusive).

I will advise you to use gedit with the embeded terminal plugin.It allows quick compiling through the embeded terminal.Perfect for quick testing.

You can use tcc as a C script engine.
$ cat tcctest.c
#!/usr/bin/tcc -run
#include <stdio.h>
int main(void) {
printf("Hello, tcc!\n");
return 0;
}
$ chmod u+x tcctest.c
$ ./tcctest.c
Hello, tcc!

http://www.compileonline.com
I found this Site more useful than ideone or codepad because it supports more languages than codepad and you can see the output of you code on an adjacent window you can also provide Standard Inputs and command line arguments and you can also access a file input.txt in your program.

Related

How to run C++ program from terminal VS Code

I want to run a C++ program in VS Code. All I get from Google is that click on run and debug (the play button) on top right in VS Code and my program will be up and running. I don't want to do from that. I want to do it from terminal.
Example, to run:
A Python file I do: python3 fileName.py
A Flutter program: flutter run
A Java file: javac fileName.java
A Go file: go run fileName.go
Is there any command similar like this in C++?
Apologies, I know my question is a little naïve.
i guess the short answer would be :
$ g++ -o < name-you-want-to-give> source.cpp
In place of replace it by any name like myprogram, etc.
./myprogram
This mean you had to install gcc compiler beforehand.
I need to be in my project directory and then i need to run
g++ 01inputFromUser.cpp -o 01inputFromUser && "/home/aman/Desktop/arjun/cpp/"01inputFromUser
so this was what I was looking for
g++ fileName.cpp -o fileName && "/path/to/project/"fileName

i don't know what is wrong with vs code in running cpp

i just started to code in cpp and nothing is working idk if i didn't install the gcc properly or what but i already set the path of the bin file idk why it refuses to run
the code:
#include<iostream>
int main()
{
std::cout<<"hello";
}
and the problem is that when I try to use the "code runner extension" it is not working so I just press f5 and then when I get the error messages which says at first "could not find the task file'c/c++:g++.exe build active file' " and I get three options 1:debug anyway
2:configure task
3:cancel
when I choose debug anyway I get this error here
Since you're on windows consider installing Visual Studio or CLion. They're more beginner friendly - VSCode can get tricky to run c++ on windows. Either way, looks like you're trying to run your project without building it first. There should be a build option right next to the run option. Try building it, then running. The build is what compiles and creates the project.exe file, which is what the compiler is saying isn't there.
The referenced IDE's always auto-build on run, so there's that
If you're familiar with using the command line, these commands will do what you want, assuming the .cpp file is in your current directory.
g++ <FILENAME>
./a.out
There are wonderful flags you can add to the first command (the compiling command) like -Wall, -Wextra, -o, and many more. But, since it seems like you're just starting out, there's no need to worry about those!
If you're not familiar with the command line, I would encourage you to become familiar! It is an extremely powerful tool for a programmer. Here is a YouTube video that talks about it.

Script for Notepad++ NppExec for C++ in ubuntu

I just switched to ubuntu and I wanted to setup notepad++ for CPP.
So I used the NppExec plugin to compile within notepad++,
My script was :
npp_save
g++ "$(FULL_CURRENT_PATH)" -o "$(CURRENT_DIRECTORY)\$(NAME_PART)obj"
./"$(NAME_PART)obj"
Here the "obj" I used is to just save the file with an "obj" keyword nothing else.
The last line ./"$(NAME_PART)obj" is to run the program.
But it looks not working in ubuntu, it produces this error:
NPP_SAVE: Z:\home\username\cpp\test.cpp
g++ "Z:\home\username\cpp\test.cpp" -o "Z:\home\username\cpp\testobj"
; about to start a child process: "g++ "Z:\home\username\cpp\test.cpp" -o "Z:\home\username\cpp\testobj"
CreatProcess() failed with error code 2:
File not found.
./"testobj"
; about to start a child process: "./"testobj""
CreatProcess() failed with error code 2:
File not found.
I have investigated some of what I think is the problem, so I think is the usage of / and \ in changing the directory.
I don't know how to fix that, so I can not be sure.
Any ideas? :) I am using vim btw in the same machine and it is working perfectly.
In theory it might be possible (see below), in practice it is rather convoluted and works only for simple compiles (like single file hello world type).
I would suggest you try a linux program, e.g.
an editor like
scite (same editing engine as notepad++) or
kate
or a real IDE like
kdeveloper or
qtcreator.
The problems with Notepad++ inside wine and g++ outside wine (from the linux install ) are this:
notepad++ inside wine under linux is still a windows program
NppExec can only do, what a cmd inside wine can do.
starting g++ directly inside cmd is an error due to g++ being a linux binary and not a windows binary
that is your CreatProcess() failed with error code 2, it means: you are trying to execute a linux program inside wine.
That does not work! (At least not so easy.)
Though you can start linux program inside cmd inside wine using start /unix ...
started this way, g++ wants linux paths and NppExec through its variables will provide only windows paths (whatever wine has set up as drives like Z:\home\username\src\hello.cpp)
though you can convert wine paths to linux paths via the winepath -u command.
g++ started through 'start /unix ... ' inside a cmd inside wine has no proper terminal to report errors to you
though you can start an xterm for g++ and have g++ reports its messages to the xterm
the downside is that g++ will report errors using the linux paths in the xterm, so you cannot double click on an error message an get to the corresponding filename and line.
You get the idea: its complicated not comfortable.
What worked for me for a helloword.cpp was this NppExec script:
NPP_SAVE
npp_run cmd /c start /unix /usr/bin/xterm -e "/usr/bin/winepath -u '$(FULL_CURRENT_PATH)' | xargs g++ -o /tmp/a.out && /tmp/a.out ; echo 'Press return'; read"
The second line
uses an xterm,
let winepath convert the Z:\home\... path to /home/... and
have that send to g++ for compilation using /tmp/a.out as binary
if compile is successfull, /tmp/a.out is executed
the echo and read are for keeping the xterm open so that you can read the output.
If you really want to use Notepad++ inside wine, one option might be using Gnu Make outside of wine and have NppExec run make all or make run similar to the g++ in my script example. That would work for more complicated compiles.

Compile C/C++ with gVim 8.1 in Windows 10 (MinGW)

Since everything is 32-bit, I used :set makeprg=mingw32-make, and then tried compiling via :!make, which gave the following error message:
'make' is not recognized as an internal or external command, operable program or batch file.
shell returned 1
I tried the basic "Goodbye World" stuff:
#include <iostream>
int main() {
std::cout << "Goodbye World";
return 0;
}
What am I doing wrong? Other than being a noob.
:!make doesn't run 'makeprg'. It runs make. Since you are specifically trying to run mingw32-make.exe, presumably you don't have an executable named make.exe. (See :help :!)
:make runs 'makeprg'. (See :help :make, :help 'makeprg')
my goal is to see the "Goodbye World" either in console or terminal or any observable way. Would this require additional tinkering to the _vimrc file?
You would rather want to do it by tinkering with your makefile. Any arguments to :make will be passed to 'makeprg'. If you defined targets clean (to remove the Make artefacts) or run (to execute the product of your Make), you will be able to write :mak clean or :mak run in Vim to run those targets. Obviously, you can create your own commands and/or mappings to make those :make commands faster.
Note (and I completely overlooked this myself, silly me) that when you run a simple code, such as the one above, that does not need extensive file managements and Makefiles, all you need to go is :!gcc % for C and :!g++ % for C++. I believe (and I may be wrong, but this is a simple observation) that in Vim, :! indicates the following commands are to be executed in the system Command Prompt, and gcc/g++ is the command to invoke the GNU Compiler for C and C++ respectively. Finally, % is used to indicate the current filename, with all extensions intact. This is extremely useful in cases of keymapping, as I have done via the following:
nnoremap <F5> :!g++ %<CR>|"Press Func.5 to Compile via GNU Comp.

What is a 'shebang' line?

Currently I'm trying to start programming on my new Mac. I installed TextWrangler, and chose C++ as my language of choice; since I have some prior knowledge of it, from when I used Windows.
So, I wrote the ever so common "Hello World" program. Although, when I tried to run it, I got an error:
"This file doesn’t appear to contain a valid ‘shebang’ line (application error code: 13304)"
I tried searching the error code to find out how to fix this, but I couldn't find anything.. I have no idea what a 'shebang' line is... Can someone help me out?
You need to compile it with a compiler first. I assume you tried to run the source file like ./source but C++ doesn't work this way.
With some compilers however, you can provide a shebang-line as the first line of the source file (the #! is known as shebang or crunchbang, hence the name), like so:
#!/path/to/compiler
So that the shell knows what application is used to run that sort of file, and when you attempt to run the source file by itself, the compiler will compile and run it for you. That's a compiler-dependent feature though, so I recommend just plain compiling with G++ or whatever Macs use to get an executable, then run that.
While I wouldn't recommend it for regular C++ development, I'm using a simple shell script wrapper for small C++ utilities. Here is a Hello World example:
#if 0 // -- build and run wrapper script for C++ ------------------------------
TMP=$(mktemp -d)
c++ -o ${TMP}/a.out ${0} && ${TMP}/a.out ${#:1} ; RV=${?}
rm -rf ${TMP}
exit ${RV}
#endif // ----------------------------------------------------------------------
#include <iostream>
int main(int argc, char *argv[])
{
std::cout << "Hello world" << std::endl;
return 0;
}
It does appear that you are trying to run the source file directly, however you will need to compile using a C++ compiler, such as that included in the gcc (GNU Compiler Collection) which contains the C++ compiler g++ for the Mac. It is not included with the Mac, you have to download it first:
from http://www.tech-recipes.com/rx/726/mac-os-x-install-gcc-compiler/ : "To install the gcc compiler, download the xcode package from http://connect.apple.com/. You’ll need to register for an Apple Developer Connection account. Once you’ve registered, login and click Download Software and then Developer Tools. Find the Download link next to Xcode Tools (version) – CD Image and click it!"
Once it's installed, if you are going for a quick Hello World, then, from a terminal window in the directory of your source file, you can execute the command g++ HelloWorld.cpp -o HelloWorld. Then you should be able to run it as ./HelloWorld.
Also, if you're coming from a Visual Studio world, you might want to give Mono and MonoDevelop a try. Mono is a free implementation of C# (and other languages), and MonoDevelop is an IDE which is very similar to Visual Studio. MonoDevelop supports C# and other .NET languages, including Visual Basic .NET, as well as C/C++ development. I have not used it extensively, but it does seem to be very similar to VS, so you won't have to learn new everything all in a day. I also have used KDevelop, which I liked a lot while I was using it, although that's been a while now. It has a lot of support for GNU-style development in C/C++, and was very powerful as I recall.
Good luck with your endeavors!
Links:
Mono: http://mono-project.com/Main_Page
MonoDevelop: http://monodevelop.com/
KDevelop: http://kdevelop.org/
shebang is http://en.wikipedia.org/wiki/Shebang_%28Unix%29.
not sure why your program is not running. you will need to compile and link to make an executable.
What I find confusing (/interesting) is C++ program giving "Shebang line" error. Shebang line is a way for the Unix like operating system to specify which program should be used to interpret the rest of the file. The shebang line usually points to the path of the interpreter. C++ is a compiled language and does not have interpreter for it.
To get the real technical details of how shebang lines work, do a man execve and get that man page online here - man execve.
If you're on a mac then doing something like this on the commandline:
g++ -o program program.cpp
Will compile and link your program into an executable called program. Then you can run it like:
./program
The reason you got the 'shebang' error is probably because you tried to run the cpp file like:
./program.cpp
And the shell tries to find an interpreter to run the code in the file. Because this is C++ there is no relevant interpreter but if your file contains Python or Bash then having a line like this
#!/usr/bin/python
at the 1st line in your source file will tell the shell to use the python interpreter
The lines that start with a pattern like this: #!/.../.../.. is called a shebang line. In other words, a shebang is the character sequence consisting of the characters number sign and exclamation mark (#!).In Unix-like operating systems, when a text file with a shebang is used as if it is an executable, the program loader mechanism parses the rest of the file's initial line as an interpreter directive. The loader executes the specified interpreter program, passing to it as an argument the path that was initially used when attempting to run the script, so that the program may use the file as input data.