Test C++ open() of a file or directory

test.cc

// Test how open() or ifstream() behave when reading a directory, file or stream.
// Written 2015 by Freek Dijkstra
// Contributed to public domain
// See http://stackoverflow.com/questions/29310166/check-if-a-fstream-is-either-a-file-or-directory

#include <iostream>
#include <fstream>
#include <cerrno>
#include <cstring>

int main(int argc, char *argv[]) {
	for (int i = 1; i < argc; i++) {

		std::ifstream my_file;
		try {
			// Ensure that my_file throws an exception if the fail or bad bit is set.
			my_file.exceptions(std::ios::failbit | std::ios::badbit);
			std::cout << "Read file '" << argv[i] << "'" << std::endl;
			my_file.open(argv[i]);
		} catch (std::ios_base::failure& err) {
			std::cerr << "  Exception during open(): " << argv[i] << ": " << strerror(errno) << std::endl;
			continue;
		}
		
		try {
			std::string line;
			while (std::getline(my_file, line))
			{
				std::cout << "  read line: " << line << std::endl;
			}
		} catch (std::ios_base::failure& err) {
			if (errno == 0) continue; // exception is raised due to EOF, no real error.
			std::cerr << "  Exception during read(): " << argv[i] << ": " << strerror(errno) << std::endl;
		}
	}
}

/*
Compiled with:
    g++ -Wall -g -std=c++11 -o test test.cc

Make test environment:
    mkdir testdir
    echo "hello world" > testdir/file_with_trailing_lf
    echo -n "hello world" > testdir/file_without_lf

Testing:
    uname -srm; ./test testdir/file_without_lf testdir/file_with_trailing_lf testdir no_such_file

Results:

Darwin 14.1.0 x86_64
Read file 'testdir/file_without_lf'
  read line: hello world
Read file 'testdir/file_with_trailing_lf'
  read line: hello world
Read file 'testdir'
  Exception during read(): testdir: Is a directory
Read file 'no_such_file'
  Exception during open(): no_such_file: No such file or directory

Linux 2.6.32-042stab092.3 i686
Read file 'testdir/file_without_lf'
  read line: hello world
Read file 'testdir/file_with_trailing_lf'
  read line: hello world
Read file 'testdir'
  Exception during read(): testdir: Is a directory
Read file 'no_such_file'
  Exception during open(): no_such_file: No such file or directory

*/