This is a Standard C Library...  but here are the changes from Standard C...

time() has been renamed to _time() to avoid name conflicts

atol() and atoi() are replaced with str2num()
          #defines are placed in qlib.h if you still use the old names

ltoa() and itoa() are replaced with num2strs()
          These are avail but simply call num2strs()
utoa() is num2str()
          Again it is avail but it simply calls num2str()
          There are many versions of num2strs():
            each following this form: num2str[c,s,sc] ();
              c=capital letters (if radix is over 10)
              s=signed (ltoa and itoa)
              sc=signed and capital letters
              Default is unsigned
            NOTE: leading zeros ARE removed (v2.00+)

open() does not need the stupid attr field when creating files and will
  make the new files writtable (unlike C which needed the dumb S_IWRITE flag)

fprintf() and vfprintf() use file handles NOT streams.  The stdout,err
 etc. are simply #defines in the stdio.h file for those handles given by DOS.