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I am trying to link libevent using g++ but am having trouble since I set libevent's install directory with the --prefix flag when configuring. To install libevent I downloaded the latest source, extracted it and ran the following commands in the directory

./configure --prefix=/home/tom/local --disable-shared && make
make install

After running these commands libevent successfully installs to the /home/tom/local folder. Now to test that I can use libevent I have downloaded the sample rot13 server with libevent that can be found towards the bottom of: http://www.wangafu.net/~nickm/libevent-book/01_intro.html

To compile I run the following command:

g++ -I=/home/tom/local/include rot13server.cpp -L/home/tom/local/lib

But I get the following compilation errors:

/tmp/cctwJY4k.o: In function `alloc_fd_state(event_base*, int)':
libevent.cc:(.text+0x9b): undefined reference to `event_new'
libevent.cc:(.text+0xec): undefined reference to `event_new'
libevent.cc:(.text+0x11a): undefined reference to `event_free'
/tmp/cctwJY4k.o: In function `free_fd_state(fd_state*)':
libevent.cc:(.text+0x1b6): undefined reference to `event_free'
libevent.cc:(.text+0x1c9): undefined reference to `event_free'
/tmp/cctwJY4k.o: In function `do_read(int, short, void*)':
libevent.cc:(.text+0x310): undefined reference to `event_add'
/tmp/cctwJY4k.o: In function `do_write(int, short, void*)':
libevent.cc:(.text+0x4da): undefined reference to `event_del'
/tmp/cctwJY4k.o: In function `do_accept(int, short, void*)':
libevent.cc:(.text+0x564): undefined reference to `evutil_make_socket_nonblocking'
libevent.cc:(.text+0x5da): undefined reference to `event_add'
/tmp/cctwJY4k.o: In function `run()':
libevent.cc:(.text+0x5f3): undefined reference to `event_base_new'
libevent.cc:(.text+0x63f): undefined reference to `evutil_make_socket_nonblocking'
libevent.cc:(.text+0x6d2): undefined reference to `event_new'
libevent.cc:(.text+0x6e7): undefined reference to `event_add'
libevent.cc:(.text+0x6f3): undefined reference to `event_base_dispatch'
collect2: error: ld returned 1 exit status

It seems like the compiler is finding the include files but not the object files.

I also tried configuring libevent without the --disable-shared option and then exported /home/tom/local/lib to the LD_LIBRARY_PATH but I still get the same error with the compile command: 

g++ -I=/home/tom/local/include rot13server.cpp
Can anyone tell me what I am doing wrong?
Thanks
tab1293
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    You need to name the library(ies) you need when you compile and link the source. You probably need to add `-levent` or `-levent_core` – rici Feb 07 '14 at 04:15
  • Wow thank you the -levent option made everything compile correctly – tab1293 Feb 07 '14 at 04:19

1 Answers1

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Can anyone tell me what I am doing wrong?

Just about everything.

The -I=/home/tom/local/include tells GCC to look in =/home/tom/local/include directory, which is unlikely to exist.

You want:

g++ -I/home/tom/local/include rot13server.cpp -c
g++ -L/home/tom/local/lib rot13server.o -levent -o rot13server
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