Linking glfw g++ [duplicate] - c++

Question

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What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 1 year ago.
I have been trying to code with OpenGL without using a IDE, but the manual linking is really confusing me. I have a folder with the libglfw3.a, glfw3.h and a .cpp file with this example code.
#include "glfw3.h"
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
I compile it like this.
g++ source.cpp -lglfw3 -o program
Yet I get these errors.
C:\Users\murra\Coding\Manual>g++ source.cpp -lglfw3 -o proc
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x17): undefined reference to `glfwInit'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x56): undefined reference to `glfwCreateWindow'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x64): undefined reference to `glfwTerminate'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x76): undefined reference to `glfwMakeContextCurrent'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x81): undefined reference to `glfwWindowShouldClose'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0x96): undefined reference to `_imp__glClear#4'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0xa6): undefined reference to `glfwSwapBuffers'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0xab): undefined reference to `glfwPollEvents'
C:\Users\murra\AppData\Local\Temp\ccO7xs1Q.o:source.cpp:(.text+0xb2): undefined reference to `glfwTerminate'
collect2.exe: error: ld returned 1 exit status
I'm quite new to this stuff so help would be appreciated.

Answer 1

When you link a third party lib, you need to "tell" the compiler the location of the headers as well as the location of the libraries.
Typically, one would use -I<header_dir> and -L<lib_dir> in addition to -l<lib_name>
You may also reduce this to 2 steps by using -I<header_dir> and -L<full_lib_path>
If linking causes errors, IMO there are 3 major reasons.
Incorrect path
Mixing shared lib and static lib flags (example - -MT and -MD on VS)
Additional library dependencies that you have not included.
In your case, the missing symbols seem to be from additional libs. Try -lglfw3 -lglew32 -lopengl32 -lgdi32 as additional options. Obviously these need to be on your computer.