I am iterating over the subdirectories in a directory. The code I have for this has always worked up until now, but now it is crashing when I create the iterator (ask "What did you change?" if you like; the answer is "If I knew that..."). My question is: what can cause the creation of an iterator to crash? Looking at the documentation, directory_iterator(my_path) throws if !exists(my_path), which is fair enough. This check is already in my code, however, and does not report that the path does not exist. Here is a (revised) segment of my code: const char* source_directory = getenv(MYENVVAR); if ((source_directory == NULL) || (source_directory[0] == '\0')) { return false; } boost::filesystem::path dir_path(source_directory, boost::filesystem::native); boost::filesystem::directory_iterator end_iterator; if (!exists(dir_path)) { return false; } boost::filesystem::directory_iterator dir_iterator(dir_path); //CRASH while (dir_iterator != end_iterator) { //do whatever I do here dir_iterator++; } The program crashes where indicated. The path exists. I've tried replacing the const char* at the beginning with a std::string (then using .c_str() where appropriate) but this makes no difference. So, apart from the path not existing, how else can directory_iterator(dir_path) cause an error? Incidental info: This works fine in Windows (albeit with a different path); this code builds a shared object for use in Shake, meaning I can't use gdb; I am working with gcc 3.2.3 and Boost 1.33.1. Paul