gcc - C compilation error, external library functions not found -

i'm trying compile project (which written on 32bit os, ubuntu). i'm using given makefiles , installed necessary external libraries (on 64bit ubuntu).

i don't library linking error functions implemented in sdl , argtable2 (external libraries) not recognized. changed path libsdl_gfx.so points 64bit installation.

how can solve compilation issue?

code:

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <argtable2.h>  #include "../../problems/generative_model.h" #include "../../problems/viewer.h" #include "opcas.h"   int main(int argc, char* argv[]) {      double discountfactor;     unsigned int maxnbevaluations;     char isterminal = 0;     char isdisplayed = 1;     char verbose = 0;     unsigned int nbtimestep = 0;     double l;      opcas_instance* instance = null;      state* crtstate = null;     state* nextstate = null;     double reward = 0.0;     double* optimalaction = null;      struct arg_dbl* g = arg_dbl1("g", "discountfactor", "<d>", "the discount factor problem"); ...     return exit_success; } 

the makefile looks like:

cc := gcc flags := -w -wall -g -ansi -std=c99 -pedantic libs := -lm -lsdl -lsdlmain /usr/lib/x86_64-linux-gnu/libsdl_gfx.so -largtable2 bin_dir := bin obj_dir := obj  all: $(bin_dir)/opcas_ball $(bin_dir)/opcas_inverted_pendulum  $(bin_dir)/opcas_mountain_car $(bin_dir)/opcas_acrobot $(bin_dir)/opcas_spring_pendulum  $(bin_dir)/opcas_ball: $(obj_dir)/opcas_1.o $(obj_dir)/main_opcas_1.o $(obj_dir)/ball.o $(obj_dir)/viewer_ball.o $(obj_dir)/opcas_drawing_procedure_ball.o $(obj_dir)/svgfile.o     $(cc) $(flags) $(libs) $^ -o $@ 

the error (similar error sdl functions):

gcc -w -wall -g -ansi -std=c99 -pedantic -lm -lsdl -lsdlmain /usr/lib/x86_64-linux-  gnu/libsdl_gfx.so -largtable2 obj/opcas_1.o obj/main_opcas_1.o obj/ball.o   obj/viewer_ball.o obj/opcas_drawing_procedure_ball.o obj/svgfile.o -o bin/opcas_ball obj/main_opcas_1.o: in function `main': /home/elod/utwork/realtime_cpp/continuous_action_space/algorithms/opcas/main_opcas.c:63: undefined reference `arg_dbl1' 

options specifying libraries need go command-line after object using symbols out of libraries given.

so command:

 gcc -w -wall -g -ansi -std=c99 -pedantic -lm -lsdl -lsdlmain /usr/lib/x86_64-linux-gnu/libsdl_gfx.so -largtable2 obj/opcas_1.o obj/main_opcas_1.o obj/ball.o obj/viewer_ball.o obj/opcas_drawing_procedure_ball.o obj/svgfile.o -o bin/opcas_ball 

should this

 gcc -w -wall -g -ansi -std=c99 -pedantic /usr/lib/x86_64-linux-gnu/libsdl_gfx.so  obj/opcas_1.o obj/main_opcas_1.o obj/ball.o obj/viewer_ball.o obj/opcas_drawing_procedure_ball.o obj/svgfile.o -o bin/opcas_ball -lm -lsdl -lsdlmain -largtable2 

as rule of thumb, work in cases: place -lxyz options @ end of link command.