Undefined symbols for architecture - strange message

Question

When I compile I get a set of strange errors. This is what i compile with first. (This is generated from my makeFile.)

gcc -Wall -g -std=gnu99 -pedantic -c error.c -o error.o gcc -Wall -g -std=gnu99 -pedantic -c agent.c -o agent.o gcc -Wall -g -std=gnu99 -pedantic -c io.c -o io.o gcc -Wall -g -std=gnu99 -pedantic -c map.c -o map.o

Then it comes down to linking it all together with my handler; I use this:

gcc -Wall -g -std=gnu99 -pedantic error.o agent.o io.o map.o handler.c -o handler

and it outputs a message that I cant find info about. Any ideas?

Undefined symbols for architecture x86_64: "_m", referenced from: _print_map in io.o _read_map in io.o _check_row in map.o _get_start_pos in map.o _move_one_step in map.o _displayMoveOnMap in map.o _reset_map in map.o ... (maybe you meant: _reset_map, _move_one_step , _print_map , _read_map , _main )

I think it's just a little Makefile tweak but I can't find much on these errors.

Are print_map(), read_map() etc your code? Looks like a missing object file. — John3136
– John3136, Commented Sep 26, 2013 at 22:49
@John3136 yeah they are all in my code. declared in the headers ect I thought i was linking them up to the handler ? — Mark Nicolle
– Mark Nicolle, Commented Sep 26, 2013 at 23:01
Please don't add "[SOLVED]" to the title of your question. That's indicated simply by accepting an answer (which you've done). — Keith Thompson
– Keith Thompson, Commented Sep 26, 2013 at 23:38

rici · Accepted Answer · 2013-09-26 22:58:52Z

1

Sounds like you've got an extern m (I don't know what type, or even if it is a function) in both io.c and map.c, but not defining it anywhere. I'd look for the extern declaration in map.h, although that's just a guess.

answered Sep 26, 2013 at 22:58

rici

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Mark Nicolle Over a year ago

Hi it was this problem and then it came up to a duplicate declaration warning, did abit of searching and for some reason i was declaring a struct NULL in the header. Thank you so much @rici

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