Question

I’m getting “undefined reference to `get_metadata_record_new'” right on the get_metadata_record_new(sz) in memory.c

{memory.c}

#include "metadata_record.h"

bool add_tohashtable(struct memory *mem, char *key_address, size_t sz) {
    //Getting the error on this next line
    struct metadata_record * metarec = get_metadata_record_new(sz);
    ...
}

{metatdata_record.h}

#ifndef METADATA_H_
#define METADATA_H_
struct metadata_record {
    size_t size;
    bool allocated;
};

struct metadata_record *get_metadata_record_new(size_t);
...
#endif /* METADATA_H_ */

I tried copying and pasting this definition from my metadata_record.c file to the top of my memory.c and the error goes away:

struct metadata_record *get_metadata_record_new(size_t sz) {
...
}

Answer 1

You have to link the two files together in order the one to see the other.

ProTip: don’t write Makefiles like

myprog: file_one.o file_two.o

you are going to forget to update them. Also, it’s just a bad concept. Instead, write Makefile like

OBJECTS = $(patsubst %.c, %.o, $(wildcard *.c))
myprog: $(OBJECTS)

That would break way less frequently.