Microsoft C offers extensions that let you take advantage of the full capabilities of the computer. These extensions are not portable to other compilers or environments. See Chapter 1, “Elements of C,” of the C Language Reference for a list of Microsoft-specific keywords.
The Run-Time Library Reference contains compatibility information for every function in the run-time library. Any function or macro that does not have the ANSI box marked may not be portable to other compilers or computer systems.