CODEWITHSUNDEEP
cmakefilelinkerlinker-errorsundefined-reference
AndroidDev
AndroidDev

Reputation: 21247

Compiling: undefined reference to

I'm struggling with compiling multiple files into a common program. I'm getting an error:

undefined reference to 'pi'

Here's the skeleton of my code and Makefile. What am I doing wrong? Thanks!

File: calcPi.c

#include <stdlib.h>
#include <stdio.h>
#include <sched.h>
#include <string.h>

#include "pi.h"

int main(int argc, char* argv[]) {
    long iterations = 1000000;
    int policy = 2;
    int numChildren = 3;
    pi(iterations, policy, numChildren);
    return 0;
}

File: pi.h

void pi(long iterations, int policy, int numChildren);

File: pi.c

#include "pi.h"

void pi(long iterations, int policy, int numChildren) {
    //lots of code here
}

I'm compiling this using a Makefile:

CC = gcc
CFLAGS = -c -g -Wall -Wextra
LFLAGS = -g -Wall -Wextra

all: calcPi pi

calcPi: calcPi.o
    $(CC) $(LFLAGS) $^ -o $@ -lm

pi: pi.o
    $(CC) $(LFLAGS) $^ -o $@ -lm

calcPi.o: calcPi.c
    $(CC) $(CFLAGS) $<

pi.o: pi.c
    $(CC) $(CFLAGS) $<

clean:
    rm -f pi calcPi
    rm -f *.o
    rm -f *~

EDIT: In response to the request for the entire error message:

In function 'main'" calcPi.c:55: undefined reference to 'pi' collect2: error: ld returned 1 exit status make: * [calcPi.o] error 1

Upvotes: 2

Views: 5001

Answers (1)

brain
brain

Reputation: 2517

First of all, is pi really supposed to be a separate application?

You're referring the pi() function from calcPi, but it's only been compiled into pi.o, so you need to add it as a dependency.

What I think you want to do, is to create calcPi using the calcPi.o and pi.o object files.

CC = gcc
CFLAGS = -c -g -Wall -Wextra
LFLAGS = -g -Wall -Wextra

all: calcPi

calcPi: calcPi.o pi.o
    $(CC) $(LFLAGS) $^ -o $@ -lm

calcPi.o: calcPi.c
    $(CC) $(CFLAGS) $<

pi.o: pi.c
    $(CC) $(CFLAGS) $<

clean:
    rm -f calc
    rm -f *.o
    rm -f *~

Upvotes: 3

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