Debugging Segmentation Faults on a Mac?

For the more modern lldb flavor

$ lldb --file /path/to/program
...
(lldb) r
Process 89510 launched
...
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x726f00)
  * frame #0: 0x00007fff73856e52 libsystem_platform.dylib`_platform_strlen + 18
...

Have you compiled with -g and run it inside gdb? Once the app crashes, you can get a backtrace with bt that should show you where the crash occurs