Question

How does one determine the environment newline¹ in C++? Google yields many results for C# and .NET but I didn’t see any way to do it for non-CLI C++.

Additional info: I need to scan a const char* for the character(s).

¹By “environment newline” I mean \r\n on Windows, \n on Linux, and \r on Mac.

Answer 1

std::endl inserts a newline appropriate for the system. You can use a ostringstream to determine the newline sequence as a string at runtime.

#include <sstream>

int main()
{
    std::ostringstream oss;
    oss << std::endl;
    std::string thisIsEnvironmentNewline = oss.str();
}

EDIT: * See comments below on why this probably won’t work.

---

If you know that your platforms will be limited to Windows, Mac, and Unix, then you can use predefined compiler macros (listed here) to determine the endline sequence at compile-time:

#ifdef _WIN32
    #define NEWLINE "\r\n"
#elif defined macintosh // OS 9
    #define NEWLINE "\r"
#else
    #define NEWLINE "\n" // Mac OS X uses \n
#endif

Most non-Windows and non-Apple platforms are some kind of Unix variant that uses \n, so the above macros should work on many platforms. Alas, I don’t know of any portable way to determine the endline sequence at compile time for all possible platforms.