Re: [Fwd: `undefined reference` Error When Linking]

On 26/03/2018 01:39, Andrew Makhorin wrote:

-------- Forwarded Message --------
From: Lam Ling
> Hi all,
> 
> 
> I built and installed glpk 4.65 from source, and I can verify that it's
> successfully installed to `/usr/local/lib`. But when I tried to compile
> a C++ program with glpk using gcc 5.4.0 on Ubuntu 16.04, I got many
> undefined reference errors on the glpk functions.
> 
> 
> Here's the g++ command I used:
> 
> 
> g++ -I/home/linuxbrew/.linuxbrew/Cellar/eigen/3.3.4/include/eigen3
> -I/usr/local/include -lm -L/usr/local/lib -lglpk -Wall -Ofast -std=c++11
> util.cpp main.cpp -o main
> 

link order matters, try

g++ -I/home/linuxbrew/.linuxbrew/Cellar/eigen/3.3.4/include/eigen3
-I/usr/local/include -lm -L/usr/local/lib util.cpp main.cpp
-lglpk -Wall -Ofast -std=c++11 -o main