Thread: Help building/linking to static library

Originally Posted by Salem

> U __ZN5Timer5startEv (in main)
> T __ZN5Timer5startEv (in lib)
Well that's exactly what I expected to see, but I'm stumped as to why it doesn't work.

So I grabbed the zip, and tried it on cygwin.

With a couple of edits to the makefile, it works.

First I got this
ar: libUtil.a: No such file or directory
So I fixed the invocation of ar

Then I got this
main.cpp:2:19: Timer.h: No such file or directory
So I fixed the FLAGS

Then all was well...

Code:

$ make
g++ -ansi -W -Wall -I. -c Timer.cpp
g++ -ansi -W -Wall -I. -c main.cpp
main.cpp:8: warning: unused parameter 'argc'
main.cpp:8: warning: unused parameter 'argv'
g++ -ansi -W -Wall -I. -o main -L. main.o -lUtil
$ ./main
123
Time elapsed: 2653000 usecs.
Time elapsed: 0 usecs.
Time elapsed: 0 usecs.
Time elapsed: 0 usecs.

The makefile now looks like this

Code:

$ cat Makefile
CC = g++
FLAGS = -ansi -W -Wall -I.

all: libUtil.a main.o
        $(CC) $(FLAGS) -o main -L. main.o -lUtil
libUtil.a: Timer.o
        @ar crs libUtil.a Timer.o
Timer.o: Timer.cpp Timer.h
        $(CC) $(FLAGS) -c Timer.cpp
main.o: main.cpp
        $(CC) $(FLAGS) -c main.cpp

Just for good measure, I did this as well

Code:

$ g++ main.o Timer.o
$ ./a.exe
234
Time elapsed: 1582000 usecs.
Time elapsed: 0 usecs.
Time elapsed: 0 usecs.
Time elapsed: 0 usecs.

If you just link both objects, does it work?
It might tell us whether it's a linker problem or a library problem.

I changed the invocation of ar to what you posted and no dice. It links successfully with Timer.o, but not libUtil.a

I just built your second OS X tarball with no problem except that you had #include <Timer.h> with the angle brackets instead of quotes. I suspect you still have a header in /usr/include. My compiler squawked about that so I changed them to double quotes and everything was fine:

Code:

whoie$ cat Makefile
CC = g++
FLAGS = -ansi -W -Wall

all: libUtil.a main.o
        $(CC) $(FLAGS) -o main -L. -I. main.o -lUtil
libUtil.a: Timer.o
        @ar rcs -v libUtil.a Timer.o
Timer.o: Timer.cpp Timer.h
        $(CC) $(FLAGS) -c Timer.cpp
main.o: main.cpp
        $(CC) $(FLAGS) -c main.cppwhoie$
whoie$ cat main.cpp
#include <iostream>
#include "Timer.h"

using std::cout;
using std::cin;
using std::endl;

int main(){
  char c;
  unsigned long usec = 0;

  Timer t; 

  for( t.start(); cin.get(c); t.reset() ) {
    usec = t.getMicroSeconds();
    cout << "Time elapsed: " << usec << " usecs." << endl;
  }

  return 0;
}
whoie$ make all
g++ -ansi -W -Wall -c Timer.cpp
a - Timer.o
g++ -ansi -W -Wall -c main.cpp
g++ -ansi -W -Wall -o main -L. -I. main.o -lUtil
whoie$ ./main

Time elapsed: 894230 usecs.

Time elapsed: 524626 usecs.

Time elapsed: 799940 usecs.
234
Time elapsed: 1963042 usecs.
Time elapsed: 1 usecs.
Time elapsed: 1 usecs.
Time elapsed: 0 usecs.
whoie$

I think you have a librarian issue. What that is....I don't have a good idea. How did you install XCode tools? Perhaps you should take this issue to an apple developer newsgroup or something. They will probably have more insight into this kind of problem. If you find out what it is, please post back. I'd hate to run into this myself someday.

Originally Posted by whoie

I just built your second OS X tarball with no problem except that you had #include <Timer.h> with the angle brackets instead of quotes. I suspect you still have a header in /usr/include. My compiler squawked about that so I changed them to double quotes and everything was fine:

Yeah - I had the library and the headers installed in their respective /usr directories (now /usr/local)

I think you have a librarian issue. What that is....I don't have a good idea. How did you install XCode tools? Perhaps you should take this issue to an apple developer newsgroup or something. They will probably have more insight into this kind of problem. If you find out what it is, please post back. I'd hate to run into this myself someday.

I'm not using XCode (except as an editor). All of the compiling/linking is done via command line with gcc/g++

Originally Posted by Kernel Sanders

I'm not using XCode (except as an editor). All of the compiling/linking is done via command line with gcc/g++

Right, but that only comes with the Xcode tools right? It's been awhile now, but I think gcc/g++ for OS X gets bundled with Xcode. Do you remember when you installed it?

Originally Posted by whoie

Right, but that only comes with the Xcode tools right? It's been awhile now, but I think gcc/g++ for OS X gets bundled with Xcode. Do you remember when you installed it?

I didn't know that. I installed about the time I got my Macbook (mid January), but I believe it has updated since