I'm doing a tutorial right now that doesn't make it to clear on how to do this.
I have two files, int2.cpp which has my main and int1.cpp which is a function (int2 calls on int1) I know they will work but how would one type it into the command line? tutorial says g++ int2.cpp int1.cpp -o int2.cpp, but it says " g++ is an illegal command"
I'm using DOSbox 0.74.
I compile things with tcc sorry but it says -o isn't a command line option
I compile things with tcc sorry but it says -o isn't a command line option
TurboC++ is an obsolete compiler (for an obsolete variant of C++); don't use it.
TinyC (e.g. the tcc command) is a compiler for C, not for C++.
C and C++ are different languages, and you want to learn at least C++11 (since older standards of C++ are obsolete and very different, it is not worth learning them in 2017).
So get and use a free software C++11 compiler like GCC or Clang. BTW both are easily available on most Linux distributions (which I recommend you to use).
Of course you'll want to compile with warnings and debug information, so use
g++ -Wall -Wextra -g with GCC and clang++ -Wall -Wextra -g with Clang.
BTW, you probably want to compile several translation units into a single executable binary. This often involves a linking step (i.e. running the linker on several object files, also using the g++ command). Consider learning to use some build automation tool like GNU make (which has a lot of builtin rules to help in doing that).
g++ is an illegal command means the compiler is not installed on your path. The syntax is (almost) right, you likely just don't have gcc installed.
g++ int2.cpp int1.cpp -o int2.exe
Related
I try to compile a robot for torcs with the usage of opendavinci. The problem is that everytime i try to compile it
#error This file requires compiler and library support for the ISO C++ 2011 standard
appears. The obvious solution is to add the support, but i have a complicated makefile that is from torcs so i dont know how to work around this problem.
Is there any way to add the support without changing the makefile? I read about the CXXFLAGS that coud help me but i dont understand how it works.
The compiler is g++ 5.4.0 for Ubuntu
felix#ubuntufelix:/usr/src/torcs/torcs-1.3.7/src/drivers/bt$ make
g++ -I/usr/src/torcs/torcs-1.3.7/export/include -I/usr/src/torcs/torcs-1.3.7 -g -O2 -Wall -fPIC -fno-strict-aliasing -O2 -DUSE_RANDR_EXT -DGL_GLEXT_PROTOTYPES -Wall -fPIC -fno-strict-aliasing -O2 -DUSE_RANDR_EXT -DGL_GLEXT_PROTOTYPES -D_SVID_SOURCE -D_BSD_SOURCE -DSHM -DHAVE_CONFIG_H -c driver.cpp
In file included from /usr/include/c++/5/array:35:0,
from driver.h:15,
from driver.cpp:1:
/usr/include/c++/5/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support \
There's no completely standard way to build distributed software, but there should be a README or INSTALL file in the distribution, which gives more-or-less precise instructions. Ideally, distributions come with a configure script, and the installation process consists of ./configure; make; make install, possibly with some per-distribution special options given to ./configure. The basic process here is that the ./configure script edits suitable values into Makefile.in to generate Makefile, but such scripts can be arbitrarily complicated. Of course, things are rarely quite that simple, and building complicated software from source can be quite a technical challenge (this is why package managers are a Good Thing).
If there are no such installation instructions (have you double-checked?), then you should go back to the software distribution point and ask for help there (you're allowed to have a hint of reproach in your question as you do so – everyone, distributing even pre-beta software, should tell users how to build things).
If you've been left high and dry, however, then the following should broadly indicate where to look next:
You need to add an option to the invocation of the compiler, to tell it to support C++ 2011 features (I'm pretty sure g++ 5.4 has these features available, but they aren't enabled by default).
You do that by adding the -std=c++11 option to the compiler flags, and the way you do that is using the CXXFLAGS makefile variable that you measured (note: CXXFLAGS is the probable/conventional name for this variable, but it's not an inviolable rule).
Depending on how the Makefile is structured, you can add or adjust that variable in a number of ways.
Edit the Makefile – search for CXXFLAGS in the Makefile and add that -std option to that definition.
You will be able to redefine the variable on the make command line: make CXXFLAGS=-std=c++11, but that will stomp on any definition within the Makefile, which might be important.
The Makefile might be structured so that the definition includes CXXFLAGS=-foo -bar $(EXTRA_CXXFLAGS), which is there precisely so that you can call make with make EXTRA_CXXFLAGS=-std=c++11.
If there's a ./configure step to building this software, then there may be an option available to ./configure when doing that step (that doesn't sound like the case here).
But one way or another, your goal is to get -std=c++11 appearing in the compiler invocation that's produced by the Makefile. Note that if you give the -n option to make, then it will show you what commands it would produce, without actually doing anything.
Have fun.
I'm using some features in my C++ programs that I need -std=c++11 option set in g++
Is it possible set this option as a default and don't be necessary use this all time I compile it?
Or how to set this in Makefile.
Yes, you typically set this in a Makefile:
CXXFLAGS=-std=c++11
One layer above you can also detect a suitable compiler via autoconf, cmake or whichever other meta-buildtool you might deploy.
You of course play games as define g++11 as g++ -std=c++11 but such set-ups are not portable.
g++-6.* will default to c++14 so at some this switch will be implicit. But it might take a really long time for all those RHEL and CentOS boxen with g++-4.4.* to disappear. Those may not even handle your current project...
Yes, upgrade to GCC 6.1:
The C++ frontend now defaults to C++14 standard instead of C++98
From https://gcc.gnu.org/ml/gcc/2016-04/msg00244.html
You can have a makefile do this as follows (this is a simple version with no variables).
out: source.cpp
g++ -std=c++11 source.cpp -o out
Use your build system of choice. Be that make, SCons, CMake, qmake or something else, and set the required option. Should take all of 30 seconds and you're done.
Or, upgrade your compiler to a version that uses C++11 by default.
I have referenced several other questions on this site and others addressing this topic and nothing has helped my issue so far.
I have two classes and a main program written in c++. Total 5 files. Everything is written originally in Visual Studio 2013 and compiles and runs there.
All are in a single folder and I use this command to compile them:
g++ myprogram.cpp
I get errors "undefined reference" errors for the contructors and destructors of both classes. Is there something obvious that I am doing wrong? If not I will post my code. Thank you.
When you invoke g++ directly like this, it will do all the steps by default, including linking. Since you haven't listed your other source files, you really just want to do compilation (it would seem) and then link the results of compiling each individual source file. You can use the "-c" option to make it just compile (rather than compile and link). Or, if you do want to build all your source files and link them together, then you should list all of the source files in question. That is:
g++ *.cpp -o yourexecutable # To compile and link all the sources
Or:
g++ -c yourfile.cpp -o yourobjectfile.o # To compile a single source
But really you shouldn't invoke g++ directly at all; there are build systems that provide a layer of abstraction on top of GCC (and other tool chains) that would be a far better, more portable, and simpler approach to building your application. For example, Bazel or Gradle would be better ways to build your program from the commandline. Though not the best or most modern build system, even using Make (and relying on its implicit rules) would be better than direclty invoking the compiler.
I have tried doing
gcc [folderName] -o [executableName]
but that does not seem to work.
gcc is used for compiling C source files but for C++ you will need to use g++. As for the multiple files, just list them:
g++ [list of all source files] -o [executableName]
Also note that if you have installed gcc via xcode then it will be quite an old version. I would recommend using clang instead as it is the compiler used by xcode and is kept up to date. It works pretty much the same as gcc so for your situation it would be:
clang++ [list of all source files] -o [executableName]
The best way is to use a Makefile as this will only compile files that have changed since the last build.
There is a nice tutorial on using make here
I have just installed MinGW and in the bin folder I can see 7 .exe files that compile my program:
c++.exe
g++.exe
mingw32-c++.exe
mingw32-g++.exe
gcc.exe
mingw32-gcc.exe
mingw32-gcc-4.4.1.exe
My small program (testprog.cpp) compiles correctly with each of them; the a.exe file is generated in the bin folder and it runs correctly.
What's the difference between them and which one should I use?
Also, what can I do to change the name of the output file from a.exe to testprog.exe automatically upon each successful compile?
These follow gcc naming conventions.
c++.exe is a traditional name for the system c++ compiler
g++.exe and gcc.exe are the names for the gcc compilers that compile for the "current system"
mingw32-* versions are the names for the compilers that cross-compile to the "mingw" target. In this case this is the same as the system target.
An then mingw32-gcc-4.1.exe is "gcc for mingw target version 4.1"
You should typically compile C code with a "gcc" variant, and c++ code with a "g++" variant.
Use -o filename in order to specify the output filename, the default is a.exe
It's quite possible that they are all the same; either exact copies or symbolic links to one another. Try using the --version flag on each to see what you've got. On my MingGW installation here, each of those binaries differs (checked with diff), but they all output the same version information (with the exception of the first bit, which is the filename):
gcc.exe (GCC) 3.4.5 (mingw-vista special r3)
Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Use the -o flag to change the output file name:
gcc -o testprog.exe testprog.cpp
In unix they'd mostly by symbolic links. The only major difference is between the 'cc' vs. '++' ones. You should notice a difference between these two if you use any part of the standard C++ library. The '++' versions link to that lib automatically. The 'cc' ones are C compilers and so don't...though you can use them as C++ compilers by just adding -lstdc++ or whatever.
While I was searching around the web for instructions in making some DLLs, I ran into a C++ compilation process that, from what I saw, used g++ to compile c++ the same way as using gcc.
I used "g++.exe"
Then in my IDE, VSCode, I also had to change the "IntelliSense mode" to "windows-gcc-x64" to get rid of the warning