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How do I check for C++11 support?
(9 answers)
Closed 4 years ago.
How can I know whether c++11 is used by default in my g++ compiler? My OS is ubuntu 18.04.1.
zell#ubuntu:~$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.3.0-27ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04)
It is--one resource out there is gcc/g++ web page on C++ status and standards:
g++ 4.8.1 and above support C++11 and I recall g++-7 having it as default
and I had seen that stated on that page before but I am not seeing it now...
g++ 6.1 and above default to C++14 as per the page
You can of course switch and make explicit choices with the usual -std=... flag.
My way (no compiler dependand): compile and run the following program
#include <iostream>
int main()
{ std::cout << __cplusplus << std::endl; }
You'll get (supposing a standard compliant compiler)
"199711", for C++98
"201103", for C++11
"201402", for C++14
"201703", for C++17
Related
I want to use https://github.com/yushangdi/parChain however I can't fullfil requirement:
Compiler:
g++ = 7.5.0 with support for Cilk Plus
I have a problem with installing GCC with Cilk. I try to follow some tutorials from the websites but any of them doesn't work correctly. Unfortunately, the Cilk project was transformed into Intel's project many documentation URLs don't work anymore. I got following error after run $./pc_exp.sh
In file included from sequence.h:27:0,
from framework.C:1:
parallel.h:25:10: fatal error: cilk/cilk.h: Not found
#include <cilk/cilk.h>
^~~~~~~~~~~~~
compilation terminated.
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.5.0-6ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-6ubuntu2)
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.5.0-6ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-6ubuntu2)
I need to run this on both: Ubuntu 20.04 and Centos 7. I'm not Linux/c++ experienced user. Can you help me with some tutorials?
I recommend you consider OpenCilk, an active open source project that picks up where Cilk Plus left off. OpenCilk 2.0 was released just a couple weeks ago, and it definitely supports Ubuntu 20.04. (Not sure about Centos.) Please see https://www.opencilk.org for tutorials on programming with Cilk (which is based on LLVM btw).
For some reason, I want to enable "-ffast-math" via pragma in g++.
But currently it doesn't work.
It seems #pragma GCC optimize("fast-math") is eventually ignored although g++ recognizes it at least during parsing this pragma sentence.
Here is a snippet I used for checking this issue(borrowed from here):
#pragma GCC optimize("fast-math")
#include <iostream>
#include <limits>
int main() {
double d = 1.0;
double max = std::numeric_limits<double>::max();
d /= max;
d *= max;
std::cout << d << std::endl;
return 0;
}
When I compiled this putting -ffast-math explicitly, this program outputs 0:
$ g++ poc.cpp -ffast-math -Wall
$ ./a.out
0
On the other hand, when I didn't put this flag, it shows 1 though I wrote the pragma sentence at least:
$ g++ poc.cpp -Wall
$ ./a.out
1
Since I confirmed other optimizations such as #pragma GCC optimize("O3") work fine(I checked with objdump), I think somehow g++ ignores only fast-math.
Does anyone know the reason or have a workaround for this?
Here is the information of g++ in my environment:
g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.10' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.10)
I use gcc-linaro-arm-linux-gnueabihf-2014.05 for cross-compling BeagleBoneBlack (Rev c) on my mac using eclipse.
I used this weblog instructions: http://www.welzels.de/blog/en/arm-cross-compiling-with-mac-os-x/
when I compile the hello world sample it works "ok" on BBB, but the problem is when I compile my full program using pthread and stdio and etc... it fails to run on BBB with the following error:
./NewDCU.elf: /usr/lib/arm-linux-gnueabihf/libstdc++.so.6: version `CXXABI_1.3.8' not found (required by ./NewDCU.elf)
for more details about my BBB:
root#arm:/home/ubuntu# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/4.8/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.8.2-19ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --disable-libitm --disable-libquadmath --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-armhf/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-armhf --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-armhf --with-arch-directory=arm --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --enable-multilib --disable-sjlj-exceptions --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=hard --with-mode=thumb --disable-werror --enable-checking=release --build=arm-linux-gnueabihf --host=arm-linux-gnueabihf --target=arm-linux-gnueabihf
Thread model: posix
gcc version 4.8.2 (Ubuntu/Linaro 4.8.2-19ubuntu1)
It seems that the problem is related to missmatch of toolchain complier version and my corresponding libraries on BBB.
I downgraded my Linaro toolchain to 4.8 from this link:
http://www.welzels.de/blog/projekte/arm-cross-toolchain/
I use ubuntu 12.04, my Makefile FC:gfortran, but I couldn't compile,
I checked on it, it installed(my gcc upgraded from 4.6.3 to 4.7)
How do I link to it?
I tried pkg-config --cflags --lib gfortran or gtkxxx, it says not in the pkg_config_path
I checked gfortran: COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' -with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
You don't need pkg-config to use gfortran; you just need to compile and link with the gfortran executable (and you can also use gfortran to link C code with Fortran code, and you could probably link using gcc with -lgfortran)
BTW, pkg-config accepts the --list-all option; with the command
pkg-config --list-all |grep -i gtk
you can understand that GTK is in fact gtk+-x11-3.0
You should also read the documentation of GFORTRAN; it has a chapter about mixed-language-programming
Of course you need to install the gfortran, gfortran-4.7 and libgfortran-4.7-dev packages
I'm debugging somebody else's Qt program and ran into the following error message which I don't understand:
DWARF-2 expression error: DW_OP_reg operations must be used either alone or in
conjuction with DW_OP_piece or DW_OP_bit_piece.
I'm not sure what that means and Google isn't of much help.
Here's the context - sLocation is a QString that was declared a few lines earlier. However, it was created from functions which were inlined, so I'm not sure of its value and am attempting to check before being appended to:
(gdb) printqstring suffix
(QString)0xffffbd80: "sorted"
(gdb) next
1241 sLocation += suffix;
(gdb) printqstring sLocation
Can't take address of "sLocation" which isn't an lvalue.
(gdb) info local
sLocation = <error reading variable sLocation (DWARF-2 expression error:
DW_OP_reg operations must be used either alone or in conjuction with
DW_OP_piece or DW_OP_bit_piece.)>
Could somebody please explain what that error message means or what could cause it?
The error message means that GDB is reading DWARF2 debug info from the executable, and is rejecting that info as invalid (not following the DWARF2 standard).
The invalid info is likely due to a bug in GCC, fixed in SVN revision 147187:
2009-05-06 Jakub Jelinek <jakub#redhat.com>
* dwarf2out.c (new_reg_loc_descr): Don't ever create DW_OP_regX.
(one_reg_loc_descriptor): Create DW_OP_regX here instead of calling
new_reg_loc_descr.
(loc_by_reference): If loc is DW_OP_regX, change it into DW_OP_bregX 0
instead of appending DW_OP_deref*.
I got the same problem running a Ubuntu 10.10 64bit. However, the same code on a 10.04 LTS 32bit works perfectly.
Here is the version output of both setups
Ubuntu 10.10:
$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.4-14ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5)
GCC on 10.04 LTS:
$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu
Thread model: posix
gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5
Cheers,
Andre