So I made a library with 2 simple functions and I wanted to add it to my codeblocks project but when I run it I get the following error: undefined reference to info::aritmetica::aduna(double, double).
What I did: I went to build options>linker settings and added the full path to my library (the name of it is info_lib.lib). And I also included the full path in the beginning of the main.cpp file (another question, how do I just use the #include "myfile.h" instead of adding the full path of the header file?)
main.cpp code :
#include <iostream>
#include "A:\Programming\info_lib\info_mai_simplu.h"
using namespace std;
int main()
{
cout<<info::aritmetica::aduna(1,2);
return 0;
}
Related
I'm writing a script which deletes old backup files. I've included filesystem as I would normally do, but this time, I got this error:
fatal error: filesystem: No such file or directory
I tried to include experimental/filesystem and I set -lstdc++fs as GCC flag. Nothing has worked for me.
Example code:
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
fs::path const directory{ "C:\Test" };
std::vector<fs::directory_entry>::size_type const num_files_to_keep{ 5 };
...
Using CodeBlocks ang GCC 8.0 or above You need to set c++17 compiler option
(I'm using CodeBlock last Nightly build).
Then you must add to the Linker settings options the stdc++fs library.
And then you must add the #include <filesystem> directive, from GCC 8.0, and not <experimental/filesystem>
On windows the directory separator is \\ (two backslash).
You need to write:
fs::path const directory { "C:\\Test" };
I am trying to write a C++ class in a separate header and cpp file using VS Code as my IDE with the 'run' and 'C++' extensions.
main.cpp
#include "Fan.h"
int main() {
Fan fan1;
return 0;
}
Fan.h
#ifndef FAN_H
#define FAN_H
class Fan {
public:
Fan();
};
#endif
Fan.cpp
#include "Fan.h"
#include <iostream>
using namespace std;
Fan::Fan() {
cout << "Fan Class" << endl;
}
I really can't seem to find anything popping out as obviously wrong. I am wondering if it is a setup problem with VS Code.
If I change #include "Fan.h" in main.cpp to "Fan.cpp" it works so it makes me think that the code works but that the linker is not setup right.
Would appreciate any help!
EDIT: Ok so I've tried the code in a different IDE and it worked. It's something to do with VS Code. Here is the error:
[Running] cd "c:\Users\<USER>\Desktop\Fan\" && g++ tempCodeRunnerFile.cpp -o tempCodeRunnerFile && "c:\Users\<USER>\Desktop\Fan\"tempCodeRunnerFile
C:\Users\<USER>\AppData\Local\Temp\cclMFKxO.o:tempCodeRunnerFile.cpp:(.text+0x57): undefined reference to `Fan::Fan()'
collect2.exe: error: ld returned 1 exit status
It sounds like the IDE is only compiling main.cpp. You need to find the command that is compiling main.cpp and ensure that it also compiles fan.cpp into fan.obj. You will also need to ensure that both main.obj and fan.obj are passed to the linker (which produces the executable program, main.exe or whatever).
There are two steps involved here:
cpp -> obj (compiling each source file into a matching object file)
obj -> exe (linking many object files into an executable)
I would say to make a CMakeLists.txt file and add main.cpp and fan.cpp into the add_executable section. Then VS can handle and run files through CMake.
this will probably a dumb question for you guy's but I have no experience in C++ what so ever. I'm using an open source project osrm (which is awesome). Still to request a route, you have make an http request. To reduce the running time, I would like to build a wrapper around the code and call it using the command line. So I googled a bit and found that osrm already creates a static lib (.a file) when compiling the project. I also found a piece of code that points me in the right directions for building a wrapper. So to begin I build a simple hello world program (see below) that includes some files from that static lib. To compile I followed this tutorial.
My directory structure looks like this:
./helloWorld.cpp
./libs/libOSRM.a
And the command to compile is this:
gcc –static helloworld.cpp –L ./libs –l libOSRM.a
The code it selve:
#include "Router.h"
#include "boost/filesystem/path.hpp"
#include "ServerPaths.h"
#include "ProgramOptions.h"
#include <InternalDataFacade.h>
#include <viaroute.hpp>
#include <iostream.h>
main()
{
cout << "Hello World!";
return 0;
}
the exact error I got:
fatal error: ServerPaths.h: No such file or directory #include "ServerPaths.h"
Add the -IPathToTheHeaderFiles to the compiler options. So it will find the files to be included. Replace PathToTheHeaderFiles with the path where your file ServPaths.h resides.
Edit: Add as many -I as you need for further header files.
Additionally it would be worth to read a book about C++ or/and the GCC manual1
1 Section 3.11 will help.
Hi I am having trouble configuring an Eclipse C++ (32bit) project to use libcurl. I am using MinGW. I am on a 64bit windows OS. I have done the following so far:
Add "libcurl.lib" to the project's Libraries
Add the path of libcurl.lib to the Library Paths
Add the path to the curl header files to the Includes path
In source, I included "curl/curl.h"
However, I am seeing the following message:
Info: Internal Builder is used for build
g++ "-LC:\\projectsrc\\Network\\curl-7.34.0-win32\\lib" "-LC:\\projectsrc\\Network\\curl-7.34.0-win32\\dlls" "-LC:\\projectsrc\\Network\\curl-7.34.0-win32\\bin" -o TestLibCurl.exe "src\\TestLibCurl.o" "-lC:\\projectsrc\\Network\\curl-7.34.0-win32\\lib\\libcurl.lib"
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -lC:\projectsrc\Network\curl-7.34.0-win32\lib\libcurl.lib
collect2.exe: error: ld returned 1 exit status
Below is the sample source
#include <stdio.h>
#include <curl/curl.h>
#include <curl/easy.h>
#include <string>
#include <sstream>
#include <iostream>
using namespace std;
int main()
{
cout << "test" <<< endl;
return 0;
}
Below is a screenshot of where I added the include path and the library file:
For your reference, I have uploaded my sample C++ eclipse project to dropbox here:
https://www.dropbox.com/s/2jowlkz6qypqe9g/TestingLibCurl.zip
The project file includes main.cpp, the libcurl.lib file, the libcurl header files, and the eclipse project setting files (.cproject, .project, .settings)
Oddly, I am able to get this to work in CodeBlocks IDE, using the same MinGW and using the same computer (Windows 64 bit). Do I need to add linker/options/flags when using Eclipse IDE?
main.cpp
#include <iostream>
#include <string>
using namespace std;
void echo(string);
int main()
{
echo("hello");
cout << "Hello world!" << endl;
return 0;
}
print.cpp
#include <iostream>
#include <string>
void echo(string code){
cout << code;
}
After compiling the code in code blocks 12.11, it gives me that error:
undefined reference to `echo(std::string)
I use windows 7 x64.
I have added the directory; Project>build options > search directories and added the current working directory.
All the files are in one console project in code blocks
I believe you should read up a bit more on namespaces usage. You are missing std in print.cpp.
Generally, while starting to learn cpp or getting a grip of the language you should always try writing full names of the classes along with the namespaces. Eventually with practice and some oversights (like now) you will learn why you really need them. In a nutshell namespaces are great:
When you are writing code over multiple files
Compartmentalize your code into separate blocks.
Also, using namespace std; should be used within cpp files mostly (otherwise headers get mangled up.
Anyways, try changing your code to this:
#include <iostream>
#include <string>
void echo(std::string code){
std::cout << code;
}
Then your results will look like this:
> g++ main.cpp print.cpp -o a.out
> ./a.out
helloHello world!
You should get more than that linker error, since you use string without any namespace in your print.cpp file. And if that source file doesn't compile it can't be linked with, and you will get the linker error you have.
Change to e.g.
void echo(std::string code) { ... }
And you do try to link with the object file created from print.cpp ?
I know this is old, but for anyone looking to solve this issue, the following may be a solution for you. If you have g++ follow c++ 11 under project->build options (check your options anyway) then you must check that box for all files you make in the project for the error to be cleared up. I had that annoying undefined reference thing too but now it is gone!
Try "Project/Properties/Build Targets tab". There you should find "Build target files" field. In that filed find "print.cpp" and click the checkbox (now the compiler will build print.cpp).
Some usefull information on Project management in CB
http://www.codeblocks.org/docs/main_codeblocks_en.html
When dealing with strings in C++ its best to sue std::string and your code seems to be wrong with a changes like using std::cout instead of plain cout another thing you need to be careful is linking your files especially files in different directories you need to tell code blocks were to find this print.cpp by going to build option and go for the search tab directory and point to where print.cpp is other wise the other approach is to just build a project which will have the main.cpp and and then add print.cpp class to current project I hope this will be of some help