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Each of the functions or macros in the C Library is described in this
chapter.  Each description consists of a number of subsections:

Synopsis:
    This subsection gives the header files that should be included within a
    source file that references the function or macro.  It also shows an
    appropriate declaration for the function or for a function that could be
    substituted for a macro.  This declaration is not included in your
    program; only the header file(s) should be included.

    When a pointer argument is passed to a function and that function does
    not modify the item indicated by that pointer, the argument is shown
    with  const before the argument.  For example,


         const char *string

    indicates that the array pointed at by string is not changed.

Description:
    This subsection is a description of the function or macro.

Returns:
    This subsection describes the return value (if any) for the function or
    macro.

Errors:
    This subsection describes the possible  errno values.

See Also:
    This optional subsection provides a list of related functions or macros.

Example:
    This optional subsection consists of one or more examples of the use of
    the function.  The examples are often just fragments of code (not
    complete programs) for illustration purposes.

Classification:
    This subsection provides an indication of where the function or macro is
    commonly found.  The following notation is used:

    ANSI
        The function or macro is defined by the ANSI C standard.

    POSIX 1003.1
        The function or macro is not defined by the ANSI C standard.  The
        function is specified in the document IEEE Standard Portable
        Operating System Interface for Computer Environments (IEEE Draft
        Standard 1003.1-1990).

    BIOS
        The function accesses a service of the BIOS ROM's found in IBM
        Personal Computers and compatibles.  These functions should not be
        used if portability is a consideration.

    DOS
        The function or macro is neither ANSI nor POSIX.  It performs a
        function related to DOS.  It may be found in other implementations
        of C for personal computers with DOS.  Use these functions with
        caution, if portability is a consideration.

    Intel
        The function or macro is neither ANSI nor POSIX.  It performs a
        function related to the Intel x86 architecture.  It may be found in
        other implementations of C for personal computers using Intel chips.
         Use these functions with caution, if portability is a
        consideration.

    OS/2
        The function is specific to OS/2.

    Windows
        The function is specific to Microsoft Windows.

    QNX
        The function or macro is neither ANSI nor POSIX.  It performs a
        function related to QNX.  It may be found in other implementations
        of C for personal computers with QNX.  Use these functions with
        caution, if portability is a consideration.

    WATCOM
        The function or macro is neither ANSI nor POSIX.  It may be found in
        other implementations of the C language, but caution should be used
        if portability is a consideration.

Systems:
    This subsection provides an indication of where the function or macro is
    supported.  The following notation is used:

    All
        This function is available on all systems.

    DOS
        This function is available on both 16-bit DOS and 32-bit extended
        DOS.

    DOS/16
        This function is available on 16-bit, real-mode DOS.

    DOS/32
        This function is available on 32-bit, protect-mode extended DOS.

    DOS/PM
        This 16-bit DOS protect-mode function is supported under Phar Lap's
        286|DOS-Extender "RUN286".  The function is found in one of WATCOM's
        16-bit protect-mode DOS libraries (DOSPM*.LIB under the 16-bit OS2
        subdirectory).

    MACRO
        This function is implemented as a macro (#define) under all systems.

    NT
        This function is available on Microsoft Windows NT, a 32-bit
        protect-mode system for Intel 80386 and upwards compatible systems.

    OS/2 1.x
        This function is available on IBM OS/2 1.x, a 16-bit protect-mode
        system for Intel 80286 and upwards compatible systems.

        When "(MT)" appears after OS/2, it refers to the CLIBMTL library
        which supports multi-threaded applications.

        When "(DL)" appears after OS/2, it refers to the CLIBDLL library
        which supports creation of Dynamic Link Libraries.

        When "(all)" appears after "OS/2 1", it means all versions of the
        OS/2 1.x libraries.

        If a function is missing from the OS/2 library, it may be found in
        WATCOM's 16-bit protect-mode DOS libraries (DOSPM*.LIB) for Phar
        Lap's 286|DOS-Extender (RUN286).

    OS/2 2.x
        This function is available on IBM OS/2 2.x, a 32-bit protect-mode
        system for Intel 80386 and upwards compatible systems.

    QNX
        This function is available on QNX Software Systems' 16 or 32-bit
        operating systems.

    QNX/16
        This function is available on QNX Software Systems' 16-bit operating
        system.

    QNX/32
        This function is available on QNX Software Systems' 32-bit operating
        system.

    Win
        This function is available on 16-bit, protect-mode Microsoft Windows
        3.x and Windows 3.x extended for 32-bit protect-mode applications
        running on Intel 386 or upward compatible systems.  This latter
        support is provided by WATCOM C/386.

    Win/16
        This function is available on 16-bit, protect-mode Windows 3.x.

    Win/32
        This function is available on Microsoft Windows 3.x, extended for
        32-bit protect-mode applications running on Intel 386 or upward
        compatible systems.  This support is provided by WATCOM C/386.