How do I run a C program from VIM?

Is there a way to compile and run a C program from VIM without typing its filename ?

:!gcc -o somename % && ./somename
When using :!, % will be substituted by the name of the currently opened file.

When your project becomes larger, you can also write a makefile and compile the current project with :make, if there are any errors, vim will jump to them automatically.

Use the following mapping code in your .vimrc file for compiling and running a c programming file.

 map <F8> : !gcc % && ./a.out <CR>

F8 key is for run the mapping. "%" is to take the current file name.

Or, if you want to save the current file before compiling it, use

map <F8> :w <CR> :!gcc % && ./a.out <CR>

Or more ideally, if you want to use the file basename not the default 'a.out' as the executable file name, use the following:

map <F8> :w <CR> :!gcc % -o %< && ./%< <CR>

In the above command, "<" after "%" removes extension and dot (foo.c => foo), so "%<" is the file basename.

You can find this and similar infos in cmdline.txt. Command in vim:help: cmdline.txt. You can also find specific details about the use of "%" by using :help filename-modifiersin vim.

TL;DR No Makefile is required, tweaking &makeprg is also completely useless, and yet :make %< is enough to compile from Vim.

Long answer:

I duplicate an answer I gave in a closed "duplicate question".

Considering we are using vim, and not vi, :make is the way to go.

On Linux-like (it also applies to cygwin, but not to mingw on windows -- in mingw case, see the other answers that alter &makeprg, leave it alone otherwise) systems where gnumake is installed, if you don't have a Makefile in your project, and if your project is made of only one file, just type :make %<. It will be enough (you can play with $CXXFLAGS, $CFLAGS, $LDFLAGS (for -Llib/path options) and $LDLIBS (for -llibname options) to tune the compilation options). Then to run the program, type :!./%<, or with latter versions of vim, run :terminal ./%<.

If your project is made of several files, then you'll need a Makefile to take advantage of :make.

If you manage your project with CMake, and if you compile your project in a directory (or several -> debug, release, ...) outside the sources tree, then the integration will require a plugin. AFAIK, I'm the only one to propose such a plugin: BuildToolsWrapper integrates the management of CMake (choice of the build directory, possibility to chose between the debug, or release, or whatever build directory). It has to be coupled with one of the local_vimrc plugin.

In all cases, calling directly the compiler from within (or outside) Vim with :!g++ -o %< % or whatever is what we used to do 15 years ago on vi. Vim has a wonderful feature: it can integrate (yes, like in IDE) the compiler. See :h quickfix. Navigating between errors directly from the editor is much easier than extracting one error line with our eyes, typing back the line number into the editor, going back to the shell to see what exactly was rejected, ... It may be enough in C, but In C++ when we are "trying to call an overload that doesn't exist", we can't work this way (switching back and forth between the editor and the shell).

Finally, if you want to compile on a single keystroke those mono-file projects, you can add in your .vimrc:

nnoremap <silent> <f7> :make %<<cr>

If you want to adapt automatically the compilation command depending of the kind of project mono-file pet project, or real world multi-file project, well, more wiring is needed, and this is what BTW does -- it reads various options to know what to do.

Last note: &makeprg is best left alone, at least not set to g++/gcc/clang/clang++/gfortran/... Because, every time you change your language, you'll have to change it (unless you use :setlocal). With the solution I recommend, if I want to use clang++ instead of g++, all I have to do is to set: :let $CXX='clang++' (or $CC in C), and then call :make %<. I can even define :let $CXXFLAGS='-std=c++11' to compile in C++11 -- the same variable will be used to turn warnings on, to use a sanitizer, etc.

It's 2018 now, vim 8 has released for 2 years and shipped with all the Linux distributions and Mac OS X. But a lot of vim tutorials are still teaching people something ten years ago.

You can compile your C++/Java programs in vim as convenience as Sublime Text or NotePad++ with some dedicated plugins for Vim 8 or NeoVim.

For example, the AsyncRun plugin will allow you run shell commands in background and read output from quickfix window in realtime. See the screen capture.

Just like compiling programs in IDEs, the compilation errors will be matched by errorformat and be highlighted and become selectable. You can navigate errors in the quickfix window or continue editing while compiling.

Quick setup

Copy & paste the lines below to your vimrc:

Plug 'skywind3000/asyncrun.vim'

" open quickfix window automatically when AsyncRun is executed
" set the quickfix window 6 lines height.
let g:asyncrun_open = 6

" ring the bell to notify you job finished
let g:asyncrun_bell = 1

" F10 to toggle quickfix window
nnoremap <F10> :call asyncrun#quickfix_toggle(6)<cr>

When you input “:AsyncRun echo hello ” in the command line:

see the capture here

You will see the realtime command output in the open quickfix window.

Compile and run a single file

Compiling a single file with AsyncRun is much simpler than Sublime Text’s build system. We can setup F9 for this:

noremap <silent> <F9> :AsyncRun gcc -Wall -O2 "$(VIM_FILEPATH)" -o "$(VIM_FILEDIR)/$(VIM_FILENOEXT)" <cr>

The macros in $(..) form will be expanded as the real file name or directory, and then we will have F5 to run the executable:

noremap <silent> <F5> :AsyncRun -raw -cwd=$(VIM_FILEDIR) "$(VIM_FILEDIR)/$(VIM_FILENOEXT)" <cr>

The double quotation mark is used to handle path names containing spaces. The option -cwd=$(VIM_FILEDIR) means running the file in the file's directory. The absolute path name $(VIM_FILEDIR)/$(VIM_FILENOEXT) is used because linux needs a ./ prefix to running executables in current directory, but windows doesn't . Using the absolute path name of the binary file can handle this crossing platform issue.

Another option -raw means the output will not be matched by vim's errorformat, and will be displayed in quickfix as what it is. Now you can compile your file with F9, check the compilation errors in quickfix window and press F5 to run the binary.

Build C/C++ Projects

No matter what build tool you are using, make or cmake, project building means acting to a group of files. It requires locating the project root directory. AsyncRun uses a simple method called root markers to identify the project root. The Project Root is identified as the nearest ancestor directory of the current file which contains one of these directories or files:

let g:asyncrun_rootmarks = ['.svn', '.git', '.root', '_darcs'] 

If none of the parent directories contains these root markers, the directory of the current file is used as the project root. This enables us to use either <root> or $(VIM_ROOT) to represent the project root. and F7 can be setup to build the current project:

noremap <silent> <F7> :AsyncRun -cwd=<root> make <cr>

What if your current project is not in any git or subversion repository ? How to find out where is my project root ? The solution is very simple, just put an empty .root file in your project root, it will be located easily.

Let’s move on, setup F8 to run the current project:

noremap <silent> <F8> :AsyncRun -cwd=<root> -raw make run <cr>

The project will run in its root directory. Of course, you need define the run rule in your own makefile. then remap F6 to test:

noremap <silent> <F6> :AsyncRun -cwd=<root> -raw make test <cr>

If you are using cmake, F4 can be map to update your Makefile:

nnoremap <silent> <F4> :AsyncRun -cwd=<root> cmake . <cr>

Due to the implementation of c runtime, if the process is running is a non-tty environment, all the data in stdout will be buffered until process exits. So, there must be a fflush(stdout) after your printf statement if you want to see the real-time output. or you can close the stdout buffer at the beginning by

setbuf(stdout, NULL);

At the mean time, if you are writing C++ code, a std::endl can be appended to the end of std::cout. It can force flush the stdout buffer. If you are developing on windows, AsyncRun can open a new cmd window for the child process:

nnoremap <silent> <F5> :AsyncRun -cwd=$(VIM_FILEDIR) -mode=4 "$(VIM_FILEDIR)/$(VIM_FILENOEXT)" <cr>
nnoremap <silent> <F8> :AsyncRun -cwd=<root> -mode=4 make run <cr>

Using the option -mode=4 on windows will open a new prompt window to run the command, just like running command line programs in Visual Studio. Finally, we have these key mappings below:

• F4: update Makefile with cmake.
• F5: run the single file
• F6: run project test
• F7: build project
• F8: run project
• F9: compile the single file
• F10: toggle quickfix window

It is more like build system in NotePad++ and GEdit. If you are using cmake heavily, you can write a simple shell script located in ~/.vim/script/build.sh to combine F4 and F7 together: it will update Makefile if CMakeList.txt has been changed, then exectute make.

Advanced usage

You can also define shell scripts in your dotfiles repository and execute the script with F3:

nnoremap <F3> :AsyncRun -cwd=<root> sh /path/to/your/dotfiles/script/build_advanced.sh <cr>

The following shell environment variables are defined by AsyncRun:

$VIM_FILEPATH  - File name of current buffer with full path
$VIM_FILENAME  - File name of current buffer without path
$VIM_FILEDIR   - Full path of current buffer without the file name
$VIM_FILEEXT   - File extension of current buffer
$VIM_FILENOEXT - File name of current buffer without path and extension
$VIM_CWD       - Current directory
$VIM_RELDIR    - File path relativize to current directory
$VIM_RELNAME   - File name relativize to current directory 
$VIM_ROOT      - Project root directory
$VIM_CWORD     - Current word under cursor
$VIM_CFILE     - Current filename under cursor
$VIM_GUI       - Is running under gui ?
$VIM_VERSION   - Value of v:version
$VIM_COLUMNS   - How many columns in vim's screen
$VIM_LINES     - How many lines in vim's screen
$VIM_SVRNAME   - Value of v:servername for +clientserver usage

All the above environment variables can be used in your build_advanced.sh. Using the external shell script file can do more complex work then a single command.

Grep symbols

Sometimes, If you don't have a well setup environment in you remote linux box, grep is the most cheap way to search symbol definition and references among sources. Now we will have F2 to search keyword under cursor:

if has('win32') || has('win64')
    noremap <F2> :AsyncRun! -cwd=<root> grep -n -s -R <C-R><C-W> --include='*.h' --include='*.c*' '<root>' <cr>
else
    noremap <F2> :AsyncRun! -cwd=<root> findstr /n /s /C:"<C-R><C-W>" "\%CD\%\*.h" "\%CD\%\*.c*" <cr>
endif

The above script will run grep or findstr in your project root directory, and find symbols in only .c, .cpp and .h files. Now we move around the cursor and press F2, the symbol references in current project will be displayed in the quickfix window immediately.

This simple keymap is enough for most time. And you can improve this script to support more file types or other grep tools in your vimrc .

That’s the practical way to build/run C/C++ projects in Vim 8 or NeoVim. Just like Sublime Text’s build system and NotePad++’s NppExec.

No more outdated vim tutorials again, try something new.