I am a c++ beginner and after reading many articles on good ways to learn programming, I have found that its a good practice to learn programming through using command line interface than through IDE's. So therefore I am trying to learn c++ through command line interface. I am following my first tutorial of a "hello world" program. I am using MinGW compiler to compile my code. As I try to compile my code in the windows command prompt, I am getting an error. I have searched throughout the internet but can't seem to find an answer for this problem. The command I use to compile my code is "g++ Motto.cpp -o Motto.exe" and I get the problem "g++:error:CreateProcess:No such file or directory". I have checked for the path environment variable and it has the MinGW path. I have also checked the MinGW folder and found that all the executives needed are installed. Please help me fix the problem.
Here is the code:
#include <iostream>
int main()
{
std::cout << "Hello world\n";
return 0;
}
That usually means the g++ cannot find some executables that it needs to run during the compilation. Especially with MinGW the installation can be little tricky.
Make sure the paths to the MinGW installation is in your PATH environment variable (echo %PATH%) and also try to restart the computer.
If you installed manually and not with the MinGW installer (mingw-get), make sure you have downloaded and installed all the prerequisities (core, c++, binutils, runtime, etc.).
The g++ --version only prints the version, so it does not need to call another executables which the compilation does (like cc/c++, ar, etc).
Check the bin folder inside your MinGW installation directory, if you have at least those executables there: cc, c++, c++filt, ld (and others like ar, as).
Also, check {MinGWDir}\libexec\gcc\mingw32{version} if it contains cc1, cc1plus, collect2.
Try running "make $file-you-want", or like #FCo said, "g++ -o Motto Motto.cpp", The error means that you're passing it an invalid filename to compile, or you're not in the proper directory. Make sure you have the file you want to compile in your working directory, either by typing "ls" or "dir" depending on the system you're using.
Information that would help answer this question:
What you're doing to cause the error (how are you running g++?)
What OS/Environment you're running on
Related
https://github.com/altf4/untwister
I wanted to use the above program to predict some PRNG. I have read the 'usage' part, I though I should use it in cmd.exe by entering the path of the untwister. I entered the path of main.cpp, only MSVC pops up. Also, MSVC doesn't allow me to debug/compile the file, so I cannot run it. I searched 'how to use untwister' on google, but there is no further instruction. I am a beginner of programming, please forgive my ignorance.
OK, based on #drescherjm comment's, I've successfully build it.
I installed msys2 and use mingw to build it. But the .exe file has
error "_zst28__throw_bad_array_new_lengthv"
I searched the error message on google, and discover that the problem
may caused by gcc version.
I downloaded an old version (10.3.0) of gcc and mingw here:
https://winlibs.com/
I typed "cd /d D:\abc" then "mingw64\bin\mingw32-make.exe" in cmd, it
showed "Nothing to be done for" error.
I discover that I can use option to force the mingw32-make.exe to
read the Makefile. I added .am to the filename of Makefile, then type
mingw64\bin\mingw32-make.exe -f D:\abc\untwister-master\Makefile.am
The mingw32-make.exe thinks that files in
D:\abc\untwister-master\prng are in D:\abc\prng, and tells me it
can't find the files.
I moved all files and folder to D:\abc, then success!
I am trying to build SOCI on Windows with a different library suffix using the CMAKE_SHARED_LIBRARY_SUFFIX option, but the script seems to ignore it.
Here is the command I run in a batch file:
cmake^
-G "NMake Makefiles"^
-DCMAKE_BUILD_TYPE=Release^
-DCMAKE_SHARED_LIBRARY_SUFFIX="-vc140-x64-mt.dll"^
..\soci.3.2.3
The documentation does not say anything about the CMAKE_SHARED_LIBRARY_SUFFIX option, but the core/CMakeLists.txt script uses it to define the SOCI_LIB_SUFFIX option, which is reported on the screen when cmake is run. However, its value is always ".dll" instead of "-vc140-x64-mt.dll", so it must be overwritten somewhere I don't know.
Any idea why is this happening and how fix it?
I have a C++ project in Ubuntu 12.04. To run the project the make file requires the following files:
1-All the .cpp files
2-All the .h files
3-Three shared libraries.
The project is fully functionall and performs according to the specifications. All the required .cpp files and .h files are available. The problem is that there is no main() function in any of the source files and the program entry point resides in one of the three shared libraries. My job is to find out the program execution pipeline and without having any main file I am not able to do that. I can't run the project in any IDE (i.e: eclipse) because there is no main function available.
Question: Can you please tell me how to find the program entry point?
P.S: I will be glad to provide any kind of information or material you may need to solve my problem.
Edit: The CMakeLists.txt file available here.
Edit 2: The build.sh file available here.
To find enty point look into each shared object with:
nm $library | egrep "T main$"
Library with main() will output something like
090d8ab0 T main
Very usefull way to visualize execution tree is to run:
valgrind --tool=callgrind ./my_executable -arg -arg ....
(you can abort execution early with Ctrl+C)
This will output callgrind.<pid> file. To visualize it run kcachegrind callgrind.<pid>.
You will need valgrind:
sudo apt-get install valgrind
and kcachegrind
sudo apt-get install kcachegrind
Build it with the debug option -g and step into the program with a debugger like gdb (or cgdb or ddd). You'll need any appropriate debug libraries libraries though.
Short of that, play with the code a bit. Try putting printf or cout statements that print internal variables in any functions that look important, and see what the program status is and how frequently they get called. If main is hidden in a library, there's probably another function somewhere that behaves like main for the purposes of the API provided by whatever library has the real main.
What's the API documentation for your libraries? (is this a school project?). It sounds odd to have a hidden main and not say anything about it.
In case you use a build system (CMake, SCons, ...) it is highly possible that the build system is also generating some files, and one of them might be containing the main() method. We use this methodology when we generate the main function in order to instantiate classes for libraries that were specifically selected in CMake-gui.
And again, it is possible that the build system deletes the generated files due to some obscure policy the original developers thought of but didn't tell you. So search through your build system files, see what is actually happening there.
Edit
So, after seeing you CMakeLists.txt:
check ${DIR_EXT}/covis/src/ci.cpp where DIR_EXT is SET( DIR_EXT "../ext/" CACHE PATH "Folder holding external libraries" )
See what's in there and let us know :)
Edit2
After seeing build.sh (execute steps in order):
1.
change
`cmake -D COMPILE_BINARY=ON ..`
to
`cmake -D COMPILE_BINARY=ON -DCMAKE_BUILD_TYPE=Debug ..`
and add the same -DCMAKE_BUILD_TYPE=Debug to the other cmake command too.
This will build your library and executable in debug mode.
2.
Now, in one of the c++ source files you have access to and you are sure will be called (the earlier the function will be calle the better), add:
asm("int $0x03");
This will create a breakpoint in your application.
(If you do not want to use this, see below).
3.
Build your application.
4.
Run it via a debugger in terminal:
gdb ./myapplication <ENTER>
(this will give you a gdb prompt)
(if you did not add the asm breakpoint from above, type in the gdb prompt: break filename.cpp:linenumber or break methodname to add a gdb breakpoint).
run <ENTER>
Now your application should stop in your function when it is executed.
You are still in the gdb prompt, so type:
bt <ENTER>
This will print out the backtrace of your application. Somewhere you should see a main function, together with filename and linenumber.
However, that setnames.sh looks interesting, see if it does not do anything funny :)
Trying to run the following:
#include<iostream>
#include<boost/filesystem/operations.hpp>
namespace bfs=boost::filesystem;
int main()
{
bfs::path p("second.cpp");
if(bfs::exists(p))
std::cout<<p.leaf()<<std::endl;
}
I got some errors in cygwin so I decided to try out netbeans, and used the following as a guide. I added all links and the following for filesystem Project -> properties -> Linker ->Libraries -> Add option -> Other -> -lfile_system as noted here. I have run a separate test using #include<boost/any.hpp> so I am not currently doubting that my boost is not installed correclty.
It seems weird to me that it is "file_system", so I also tried "filesystem" but to no avail.
When i hold Ctrl and click on #include<boost/filesystem/operations.hpp> my netbeans brings up my operations.hpp file so it seems okay (linked properly internally that it can "see" what I want it to see).
The solution to installing boost came in the following form:
1 - If you have any path variables that are being used for Visual Studio you should temporarily change the variable during installation. This is a good guide. Once that is done, this is one step completed.
2 - Download and install MinGW. This is a very easy process and you can find the installer files here.
Once you have done these things (if you are in the same situation as me), you will now be able to properly install boost.
Horay!
Using Boost with cygwin step by step
Create a new Project
It is better to take the names given here in this tutorial exactly. Later ask: It does not work, can then be easier to find.
I do not think I need to mention all T:\ must of course be replaced with your drive.
Project Name : Boost-cyg-Test
Now your Project should look like
Open main.cpp
Overwrite the generated code with the following. We want to that, first of all everything works without error.
Therefore, please do not use your own special code.
It is difficult to find a fault. Then told after several ask, to get:
I have used my own code
#include <iostream>
#include <boost/filesystem.hpp>
using namespace std;
using namespace boost::filesystem;
int main()
{
path p("second.cpp");
if (exists(p)) { std::cout<<p.leaf()<<std::endl; }
}
In this section we assume that "boost" is already compiled.
goto Tools -> Options
Your C++ Code Assistance options should look something like this.
If this is not so, we should let Netbeans create that for us.
Add New Tool Collection
After we have completed this dialog with OK, we should find the settings shown above. ( C++ Code Assistance options).
Copy all libs into the right place
Let's create a new folder 'boost'.
With a search tool, search in your compiled Boost folder for *.a
My Boost is compiled with the shared option so we find :
For our short App. we need only 2 files.
libboost_filesystem-gcc45-mt-d-1_53.dll.a
libboost_system-gcc45-mt-d-1_53.dll.a
But if we're at it to copy two files, we can copy all files.
So mark all found .a files and copy them into the directory just created
T:\cygwin\lib\boost .
Now we do the same with our .dll files.
Mark all .dll files and copy it in your ?:\cygwin\bin directory.
If you only have compiled static librarys, you can skip this point.
Now it's time to modify our project settings.
As you can see i put my source Boost folder into cygwin
and
As we have already noted above, we need two .a files.
with Add Library navigate to T:\cygwin\lib\boost and select
libboost_filesystem-gcc45-mt-d-1_53.dll.a
libboost_system-gcc45-mt-d-1_53.dll.a
Now you'll notice that this name was shortened by netbeans to:
boost_filesystem-gcc45-mt-d-1_53.dll
boost_system-gcc45-mt-d-1_53.dll
This is somewhat confusing. It looks as if a .dll is standing here. But it is really a .a file.
Set a breakpoint in main.cpp. Now we start debug.
I have marked the important part, the two libs, with an arrow.
All libs are found and after make has finished, stops at the breakpoint.
The output:
Build Boost for Cygwin
For all who want to create boost with shared library itself.
Download boost_1_53_0.zip
Create a folder in your ?:\cygwin directory.
boost_1_53_0
Extract the zip file into that directory.
It should look like:
open a cmd window, cd to boost_1_53_0 directory.
To have a clean build we need a PATH that have only the cygwin home and bin.
In the cmd type.
SET PATH=T:\cygwin;T:\cygwin\bin
and test the path.
PATH
Type
bootstrap.bat
Type
.\b2 --build-dir=T:\boost-cyg toolset=gcc variant=debug link=shared runtime-link=shared
After some time the build is finished.
Now you have the same environment that we have used in the tutorial.
If you get a Error : gcc not found
copy (not rename) in ?:\cygwin\bin folder, for example : (names may differ).
i686-pc-cygwin-gcc-4.5.3.exe to gcc.exe
and
i686-pc-cygwin-g++-4.exe to g++.exe
Hope it helps you.
Could you paste the error you get when compiling ?
I am not used to compile programs in a Windows environment, but I think as Jesse Good suggested in a comment that you have a linker error.
You may solve it by using -lboost_filesystem instead of lfile_system.
To find out how your libs are called, you get the name of your lib (on my unix environment I have libboost_filesystem.so), strip the "lib" prefix and the ".so" or ".a" suffix (must be different in a Windows environment).
if your boost installation is correct and you are sure about it then for Unable to resolve identifier try Code Assistance->Reparse Project from context menu of the project. It tries to recover broken code model by reparsing project from scratch. if that didn't workout try closing IDE and removing code model cache.
p.s. do you have compilation errors?
I'm trying to get up and running with Boost, so I'm trying to compile the simple example problem from Boost's "Getting Started" page. I've had two issues, and I'm not sure they're related (I'm better than a novice, but not by much) but maybe they're related...
1st issue: the "tar --bzip2 -xf /path/to/boost_1_49_0.tar.bz2" command didn't work (yes, I put the correct path in, but it gave me some errors, I forget what they were) so I used "tar -xjvf " from the directory where boost_1_49_0.tar.bz2 was located. That de-compressed the zip file and I proceeded with the example...
2nd issue: The example.cpp file will not compile, the first statement in the code is #include "boost/lambda/lambda.hpp" but then for every header file lambda.hpp is trying access, there's a "No such file or directory" compile error. For example, here are two (of the six, and I get errors for all 6) header files within lambda.hpp and the errors displayed by the cygwin compiler:
boost/lambda/lambda.hpp:14:33: boost/lambda/core.hpp: No such file or directory
boost/lambda/lambda.hpp:21:52: boost/lambda/detail/operator_actions.hpp: No such file or directory
If it helps, this is the command I'm running to compile (I generally create the executable in a separate -o command):
g++ -c example.cpp
Why can't the system find these? I added the installed directory (path/to/boost_1_49_0) to the PATH variable before I started so I know that's no it. Thanks for any advice...
(I've looked on stackoverflow and there were similar issues, but no solutions that worked)
It looks like you've already solved the first issue: namely, that you must specify the -j flag on tar to untar a bzip2'd file.
For the second issue, you need to specify boost on your include path, either by specifying it with the -I command line option or via the CPLUS_INCLUDE_PATH environment variable.