Using Low-Level I/O Functions
Many functions in the C compiler libraries are not ANSI C Standard Library functions. In general, LabWindows/CVI implements the ANSI C Standard Library.
The low-level I/O functions open, close, read, write, lseek, and eof are not in the ANSI C Standard Library. You can use these functions along with sopen and fdopen if you include lowlvlio.h.