I am trying to run some experiments using a set of functions inside a file called coco.c (from the coco optimisation platform which can be found at https://github.com/numbbo/coco). This file also comes with a header file coco.h. I have been trying to test if the calling functions from the coco.c file works by writing my own file called testing.c.

The full testing.c file can be seen below

#include <math.h>
#include <stdlib.h>
#include <stdio.h>

#include "coco.h"

#define max(a,b) ((a) > (b) ? (a) : (b))


int main(void){
 coco_suite_t *suite;
 suite = coco_suite("bbob-biobj", "", "");
 return 0;
}

I have placed placed both coco.h and coco.c in the same folder as testing.c along with my Makefile.in. coco_suite is a function inside coco.c.

The makefile that I have been using can be seen below (most of which I have copied from the example makefile).

## Makefile

LDFLAGS += -lm
CCFLAGS ?= -g -ggdb --std+c89 -pedantic -Wall -Wextra -Wstrict-prototypes -Wshadow -Wno-sign-compare -Wconversion


all: testing

clean:
    rm -f coco.o
    rm -f testing.o testing


testing: testing.o coco.o
    gcc ${CCFLAGS} -o testing coco.o testing.o ${LDFLAGS}

coco.o: coco.h coco.c
    gcc -c ${CCFLAGS} -o coco.o coco.c

testing.o: coco.h coco.c testing.c
    gcc -c ${CCFLAGS} -o testing.o testing.c

However, when attempting to build the executable I get an error saying undefined reference to coco_suite. I know that the function prototype is in the header file and the full code is in the source file as I have successfully run the example provided by the authors of the coco platform. I have doublechecked the whitespace (tabs vs spaces etc) and it matches exactly with the working example provided. However even when I copy and paste the example code into the testing.c file I get the same error.

This leads me to believe that the issue is in the makefile but I cant see what it is.

Does anyone know what the issue could be?