I am trying to install the hep-mc library listed here: https://github.com/cschwan/hep-mc for use on compute using the instructions listed in the documentation here: https://github.com/cschwan/hep-mc#installation . To compile one of the example files, I typed this into the terminal:
g++ -L/usr/local/hep-mc/include vegas_mpi_ex.cpp -o vegas_mpi
but I get these error messages:
mpi_vegas_ex.cpp:1:22: error: hep/mc.hpp: No such file or directory
mpi_vegas_ex.cpp:2:26: error: hep/mc-mpi.hpp: No such file or directory
mpi_vegas_ex.cpp:8:17: error: mpi.h: No such file or directory
in the beginning of my code, the declarations are like this:
#include "hep/mc.hpp"
#include "hep/mc-mpi.hpp"
#include <mpi.h>
The tutorial states that I should point the compiler to the location of the "include" folder that contains all the .hpp files, which I have done. Do you guys have any idea as to what I'm doing wrong?
It should also be noted that the compiler cannot find the mpi.h directory even though I have loaded the openmpi module.
-L sets paths where the linker searches for libraries to link. The option you're looking for is -I, which sets the paths where the compiler searches for #included files.
g++ -L/usr/local/hep-mc/include vegas_mpi_ex.cpp -o vegas_mpi
Oops!
g++ -I/usr/local/hep-mc/include vegas_mpi_ex.cpp -o vegas_mpi
-L specifies the path to library files; -I specifies the path to includes.
This is confusing because in terms of project management and distribution, we consider "the library" to include both binaries and header files, as well as documentation and all sorts of goodies. But at a technical level that is not what "library" means.
Related
Good day,
I have a file that I'm trying to compile and within it has an #include to a statically linked binary.
#!/bin/bash
g++ -Wall -std=c++17 Message.cpp ../textmagic-rest-cpp/lib/libtextmagic.a
I am getting the following error: fatal error: libtextmagic.h: No such file or directory
The relative path that I provided is correct under the assumption that the current working directory is the directory in which the script is called/ran. I might be linking the binary incorrectly and I've searched around the internet but the other posts/resources did not help me.
Note that the script is run in the same directory as Message.cpp.
g++ has the -I and -L flags that do that for you. Your flag will look like this: -I/ThePathToYourHeaders and -L/ThePathToYourLib. I don't know if g++ supports relative paths there but absolut paths are guaranteed to work there.
Also you probably need to add a linker flag. For your project it will be -ltextmagic. It is just the name of the .a file you want to link with, without the lib in front of the filename.
The #include directive needs to "read" the header file you give it as argument, and that is not included in the static library.
You can either include using a relative path to the source file or pass the location of the header file to the compiler using the -I argument.
i have two folders named Source and powerserver in my home directory. In source direectory i have some code related to project and it uses a .h header file from power server directory. when am compiling using make -f somename.lnx32 I am getting the below error.
error: cst.h no such file or directory.
I am new to this i dont know how to access that .h file ?
GCC looks in several different places for headers. On a normal Unix system, if you do not instruct it otherwise, it will search in default directories.
You can add directories to this list with the -I command-line option. All the directories named by -I are searched, in left-to-right order, before the default directories.
Try gcc -c -I/path_to_powerserver_directory to include header files in GCC search path.
Currently this particular header file is not found to gcc in it's search paths.
It's tagged Linux so i guess you use GCC.
#include <someheader.h> means to search someheader.h in system directories (ie. /usr/include), which you can override using the -Ipath option with GCC.
But in your case, you should be using #include "someheader.h" with the correct user path in your Makefile with the -iquote option.
The libraries that I've used so far require installation. So they generate xx.a file that can be included in the code in cygwin. However, NTL library for windows only requires to unzip the file. So I need to know how to use it in cygwin command line. I have done #include in the code. The problem is in include directory in NTL all files are " .h".
What I have done is:
g++ -c Polynomial.cpp -L/cygdrive/c/cygwin/home/Win7/libpaillier -
l:libpaillier.a -L/cygdrive/c/cygwin/home/Win7/Cryptopp -l:libcryptopp.a -
L/cygdrive/c/cygwin/home/Win7/WinNTL-9_2_0/include/NTL -lgmpxx -lgmp
but I get below error:
fatal error: NTL/ZZ.h: No such file or directory
#include <NTL/ZZ.h>
^
compilation terminated.
It'd be great if someone give me a clue. TBC: I have already installed GMP and been using it.
In gcc path to headers location is specified with -I switch. With -L you define paths to compiled libraries location (directories with .a or .so files).
Also if full path to zz.h is /cygdrive/c/cygwin/home/Win7/WinNTL-9_2_0/include/NTL/zz.h then NTL should not be included in path specified in gcc arguments.
So, you need at least to replace
-L/cygdrive/c/cygwin/home/Win7/WinNTL-9_2_0/include/NTL
with
-I/cygdrive/c/cygwin/home/Win7/WinNTL-9_2_0/include
and maybe for others libraries as well and add paths to compiled libraries locations with -L where they are needed.
I installed OpenBlas and could compile C programs linked to OpenBlas by using
gcc testOpenBlas.c -I /opt/OpenBLAS/include/ -L/opt/OpenBLAS/lib -lopenblas
If I try to link c++ programs using g++ and the same linker options I get the error:
testOpenBlas.cpp:1:28: fatal error: OpenBlas/cblas.h: No such file or directory
#include <OpenBlas/cblas.h>
Any hints?
Here is what I did:
I had to recompile OpenBlas again with g++.
I found that the common.h file exists in the source folder, so I had to include it instead of the installation folder '/opt/OpenBlas'. I still use '-L/opt/OpenBLAS/lib' flag.
Then the problem was solved.
This include directive is looking for the path OpenBlas/cblas.h in all your include directories, in particular also in /opt/OpenBLAS/include/.
So the question is: does there exist a file /opt/OpenBLAS/include/OpenBlas/cblas.h?
Also I think you might have to specify the -I flag before the source file.
Ok, so it's been a while, and i'm having problems with #includes
So I'm doing
#include "someheader.h"
but it's giving me
fatal error: someheader.h: No such file or directory
It's a system wide library I guess you could say.
I'm running arch linux and I installed the library from the repo, and I think the .h files are in /usr/include.
I could just copy all the header files into the folder my code is in but that would be a hack.
What is the "right" way to do this?
Edit: I wasn't correct by saying the .h files were in /usr/include, what I meant was that the library folder was in there
So, Emile Cormier's answer worked to a certain extent.
The problem now is that there are some include in the header file and it seems from the methods I'm trying to access that those includes are not happening
it's giving my the error
undefined reference to Namespace::Class::method()
Edit:
Ok so the final answer is:
#include <library_name/someheader.h>
And compile with
g++ code.cpp -llibrary_name
Sometimes, header files for a library are installed in /usr/include/library_name, so you have to include like this:
#include <library_name/someheader.h>
Use your file manager (or console commands) to locate the header file on your system and see if you should prefix the header's filename with a directory name.
The undefined reference error you're getting is a linker error. You're getting this error because you're not linking in libsynaptics along with your program, thus the linker cannot find the "implementation" of the libsynaptics functions you're using.
If you're compiling from the command-line with GCC, you must add the -lsynaptics option to link in the libsynaptics library. If you're using an IDE, you must find the place where you can specify libraries to link to and add synaptics. If you're using a makefile, you have to modify your list of linker flags so that it adds -lsynaptics.
Also the -L <path_to_library> flag for the search path needs to be added, so the linker can find the library, unless it's installed in one of the standard linker search paths.
See this tutorial on linking to libraries with GCC.
You'd use #include <someheader.h> for header files in system locations.
#include "someheader.h" would try to include the file someheader.h in the directory of your .c file.
In addition to including the header file, you also need to link in the library, which is done with the -l argument:
g++ -Wall youprogram.cpp -lname_of_library
Not doing so is the reason for the "undefined reference .. " linker errors.
The quick fix is to do use:
#include <someheader.h>
assuming that someheader.h is in the standard include locations (to find it use the command locate someheader.h in a shell. If it is in /usr/include it is in a standard location. If it is in a subdirectory of /usr/include you only need to add the part of the directory up to /usr/include in the #include directive (e.g. #include <fancy_lib/someheader.h>)
However, this is only half of the story. You also will need to set up your build system in a way that locates the given library and adds its include path (the path under which it's header files are stored) to the compiler command (for gcc that is -I/path/to/header). That way you can also build with different versions by configuring them in your build system. If the library is not header-only you will also have to add it to the linker dependencies. How this is achieved in your build system is best found out by consulting its documentation.