strdup or _strdup?

Question

When I use strdup in Microsoft Visual C++, it warns me:

warning C4996: \'strdup\': The POSIX name for this item is deprecated. Instead, u

Answer 1

strdup is POSIX:

http://pubs.opengroup.org/onlinepubs/9699919799/functions/strdup.html

_strdup is Windows specific:

http://msdn.microsoft.com/en-us/library/y471khhc(v=vs.80).aspx

On Unix, use strdup. On Windows, use _strdup. It's that simple. If you need to write portable code between Unix and Windows:

• use system dependent macros (for example _WIN32 vs. _POSIX_VERSION) to select the proper function (but notice that the macros may depend on specific pre existing include files):

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/unistd.h.html

http://msdn.microsoft.com/en-us/library/b0084kay(v=vs.80).aspx

• use standard functions to reimplement strdup: strlen, malloc and memmove.

• use a cross platform utility library, like glib:

http://developer.gnome.org/glib/2.28/glib-String-Utility-Functions.html#g-strdup

Note that Visual C++ message suggests that _strdup belongs to the C++ standard, but this is false, as it can be verified on the C++ standard. It merely uses the underscore prefix as a "namespace" for the function.

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3376.pdf