Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

Whenever I try to compile this code it always ends up with this error:

    In file included from /usr/include/wchar.h:6:0,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/cwchar:44,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/bits/postypes.h:40,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/iosfwd:40,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/ios:38,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/ostream:38,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/iostream:39,
             from test.cpp:1:
    /usr/include/sys/reent.h:14:20: fatal error: stddef.h: No such file or directory
    #include <stddef.h>
    compilation terminated.
The code I was trying to compile is:
#include <iostream>
using namespace std;
int main()
    cout << "Hello World! :D";
    return 0;
                try g++ file.cc where file.cc is the name of yoru file (should end in .cc or .cpp). If you still get the same error then your compiler installation is broken; fire up the Cygwin installer and refresh your installation of g++. Check that gcc and glibc are up to date also.
– M.M
                Jul 24, 2015 at 3:10
                @Chol Nhial I compile the code with using the command: g++ test.cpp I also tried g++ test.cpp -o main.
– Louie
                Jul 24, 2015 at 22:22
                @Matt McNabb: I've re-installed g++ but it still gives me that error, where can I find the gcc and glibc?
– Louie
                Jul 24, 2015 at 22:24
                How is that even possible? How does the setup program manage to install the wrong versions of packages on a fresh install? Also how do you perform the update? I'm running setup again, and there does not appear to be an option to update anything.
– jww
                Oct 23, 2015 at 11:07
                Still relevant today - installed gcc-core and gcc-g++ for the first time on an existing Cygwin install, and it installed a back level version of gcc-g++, I had to re-run setup.exe and it updated it.
– EightBitTony
                Mar 1, 2016 at 17:45
                cygwin package manager apt-cyg or sage: sage remove gcc-core gcc-g++ && sage install gcc-core gcc-g++
– U007D
                Aug 24, 2016 at 22:36
                If you are using Babun and @nishpatel's answer did not work for you, try also run pact update cygwin-devel.
– David Hoksza
                Jan 21, 2017 at 18:38
I had this error on a fresh MinGW install, it had nothing to do with the installed packages mentioned in the current accepted answer by "Prasanth Karri". In my case the issue was caused by -nostdinc in my Makefile. I actually only needed that compiler flag when building for a different target platform (not when using MinGW) so I fixed the issue by removing that flag from MinGW builds.
                Probably the still-accepted answer by "ThisIzKp". Sorry that past me didn't feel the need to link it. :-(
– Ben
                Jan 12, 2020 at 21:49
In order to update it, follow below.
If you are on Windows, just run these on command prompt or powershell
Update the package list: mingw-get update
After updating the package list, run: mingw-get upgrade
Source: How to update GCC in MinGW on Windows?
When I was incorporating a software library written in C into an existing demo project(used a C++ mbed library) I encountered this problem. The demo project would compile just fine, but after I replaced the existing main file by my own, this error occurred. 
At this point I hadn't yet thought about the fact that the mbed library that I needed was written in C++. My own main file was a .c file that #include the mbed header file. As a result I used my normal C source as if it was a C++ source. Therefore the compiler that was used to compile my main file was the C compiler.
This C compiler then encountered a #include of a module that actually does not exist (within its scope), as it's not a C++ compiler.
Only after I inspected the output of the build log I realised the various source C and C++ files were compiled by more that 1 compiler(the c++ compiler). The project used used compilers arm-none-eabi-c++ and arm-none-eabi-gcc (for embedded systems) as seen below. 
Compile log:
Building file: ../anyfile.cpp
Invoking: MCU C++ Compiler
arm-none-eabi-c++ <A lot of arguments> "../anyfile.cpp"
Finished building: ../anyfile.cpp
Building file: ../main.c
Invoking: MCU C Compiler
arm-none-eabi-gcc <A lot of arguments> "../main.c"
In file included from <Project directory>\mbed/mbed.h:21:0,
                 from ../main.c:16:
<Project directory>\mbed/platform.h:25:19: fatal error: cstddef: No such file or directory
compilation terminated.
Of course in a C++ environment cstddef exists, but in a C environment cstddef doesn't exist, in stead it's just C's implementation of stddef.
In other words, cstddef does not exist in the C compiler.
I resolved this problem by renaming my main.c file to main.cpp and the rest of the code compiled smoothly too.
TLDR/Conclusion: When building a C++ project, avoid mixing C files with C++ files(sources and headers). If possible rename .c files to .cpp files to use the C++ compiler in stead of the C compiler where required.
This problem was solved for me as I installed codeblocks with mingw compiler then I copied the mingw folder from codeblocks to C drive and added 
C\mingw\bin to the  environment variables.
                Welcome to SO, we appreciate your input! Please edit your question so that it explains why it might be working. For more, see stackoverflow.com/help/how-to-answer
– B--rian
                Aug 14, 2019 at 6:59
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.