This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 4 years ago.
I want to link against a project installed, rather than OS installed, version of GLFW to make my project more portable. I am trying to use both premake and gcc directly but they both fail.
The glfw directory is in project/libraries/glfw-3.2.1
I tried to build glfw by doing:
cd project/libraries/glfw-3.2.1
mkdir bin
cd bin
cmake ..
make all
however I do not see any binary on that directory although I did find the file libglfw3.a
So I tried to build it manually as follows:
g++ main.cpp -I libraries/glfw-3.2.1/include/ -L libraries/glfw-3.2.1/bin/src/libglfw3.a
However that fails to link as none of the glfw objects are found. i.e
I get errors like:
/usr/bin/ld: main.cpp:(.text+0x27): undefined reference to `glfwWindowHint'
try this
g++ main.cpp -I libraries/glfw-3.2.1/include -L libraries/glfw-3.2.1/bin/src -lglfw3
Using -L you are telling the compiler where the library lies but you should use -l to link it
Related
This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 9 months ago.
I've been trying to figure out why those functions are undefined. I have been looking for hours trying to find a solution and haven't found any that worked. The closest one told me to download an earlier version of SDL_image, which worked but then told me SDL.dll was missing, insisting that I would need to use an older version of SDL.
Exact error message:
This is what my Makefile looks like:
g++ main.cpp -Isrc/include -Isrc/include/SDL2 -Iinclude/headers -Lsrc/lib -g -o main -lmingw32 -lSDL2main -lSDL2 -lSDL2_image
This is what my lib folder looks like:
And yes, the include folder does have SDL_image.h
Additional question, I want to put all my .dll files in a bin folder but I don't know what is telling what, where to look for them so I have them all in the src directory:
Whoever comes across this error use the VC development libraries instead of the one for MinGW. For a reason I am not aware of it works.
This question already has an answer here:
Libraries in /usr/local/lib not found
(1 answer)
Closed 2 years ago.
I try to link a shared library just installed on my system, but for some reason the output doesn't want to execute. This is my compilation:
gcc -o test test.c -lgpio
When running the output, I get the following error:
./test: error while loading shared libraries: libgpio-3.0.0.so.3: cannot open shared object file: No such file or directory
Which is weird since I have this exact file in my /usr/local/lib-folder (along with libgpio-3.0.0.so and the other shared library files). I don't have much experience with GCC, so can someone please explain what went wrong?
Your library folder is probably not in the default search path. You'll need to specify it using the -L option when you compile:
gcc -L /usr/local/lib-folder -o test test.c -lgpio
You'll also need to add this folder to the LD_LIBRARY_PATH environment variable when you run the program.
This question already has answers here:
gcc/g++: "No such file or directory"
(3 answers)
Closed 3 years ago.
I have exported
/home/username/mesa/lib
LD_LIBRARY_PATH and tried to link the libraries, but I do not know what I have type wrong to compile the program.
So I tried to compile testing.cpp with the g++ command and it says :
fatal error: osmesa.h: No such file or directory
#include <osmesa.h>
I suppose I have typed wrong the command.
The command I tried: g++ testing.cpp -L/home/username/mesa/lib/libOSMesa.so -lmesa -s -Lmesa -lOSMesa -lGLU
Source code of testin.cpp:
#include <osmesa.h>
int main()
{
return 0;
}
libraries in side /home/username/mesa/lib:
libOSMesa.la libOSMesa.so libOSMesa.so.8 libOSMesa.so.8.0.0
You must pass the include directories as well, use the -I compiler option.
This is because the compiler will by default not look for headers in your home directory (it will do that for system installed libraries in /usr/include).
I'm trying to include the MQTT-C-Client-Library in a simple C++ project.
I have included the header file succesfully like this #include "MQTTClient.h". Compiling it in the linux terminal was printing this errors:
[xy#localhost mosquittoProject]$ sudo g++ *.cpp -o MQTTTest
/tmp/ccHn3s6m.o: In function `main':
mosquitto_test.cpp:(.text+0x11e): undefined reference to `MQTTClient_create'
mosquitto_test.cpp:(.text+0x13f): undefined reference to `MQTTClient_connect'
collect2: error: ld returned 1 exit status
I figured out that I need to link the library after some googling: Example MQTT Client Code not working C
Based on this question and answer I tried compiling it again like this:
sudo g++ -L/home/xy/Desktop/paho.mqtt.c/build/output/ *.cpp -l paho-mqtt3c -o MQTTTest
Which compiles fine but when running I get still an error.
Console commands and output:
[xy#localhost mosquittoProject]$ sudo g++ -L/home/xy/Desktop/paho.mqtt.c/build/output/ *.cpp -l paho-mqtt3c -o MQTTTest
[xy#localhost mosquittoProject]$ ./MQTTTest
./MQTTTest: error while loading shared libraries: libpaho-mqtt3c.so.1: cannot open shared object file: No such file or directory
I replaced the actual username by xy in this post.
What am I doing wrong here?
The problem looks like the library (libpaho-mqtt3c.so.1) is not on the library path.
It looks like you are linking against the build location of the library and have not installed it to the default system location (e.g. /usr/local/lib) by running sudo make install.
By default on Linux the runtime linker searches the locations listed in /etc/ld.so.conf and /etc/ld.so.conf.d. if you edit these remember to run sudo ldconfig to update the cache.
You can add the location of the library to the LD_LIBRARY_PATH environment variable e.g.:
$ LD_LIBRARY_PATH=/home/xy/Desktop/paho.mqtt.c/build/output/ ./MQTTTest
This question already has answers here:
Why does the order in which libraries are linked sometimes cause errors in GCC?
(9 answers)
Closed 8 years ago.
I'm trying to compile a C++ application using libpq.
On my Debian it compiles fine with the following command:
g++ -I /usr/include/postgresql/ -L /usr/lib/postgresql/9.3/lib/ -lpq -o test test.cpp
On my Ubuntu I get the following error:
undefined reference to 'PQfinish'
I've included link to postgresql headers and libraries and used the -lpq. What am I missing?
Move -lpq to the end of the command line.
Linking is done in the order specified, and objects are only taken from libraries if they are needed to resolve symbols at that point. So each library has to come after any other object that needs it.