IIRC, he provides a file named something along the lines of std_lib_facilities.h, which you're supposed to include in your programs. It likely contains the functions you're missing.
Thanks Athar, but I couldn't get std_lib_facilities.h to work. I copied this header from his website and put it in the same folder, but my compiler gives this error:
This file includes at least one deprecated or antiquated header which \
may be removed without further notice at a future date. Please use a \
non-deprecated interface with equivalent functionality instead. For a \
listing of replacement headers and interfaces, consult the file \
backward_warning.h. To disable this warning use -Wno-deprecated.