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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.

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
        These functions or macros are defined by the ANSI/ISO C standard.

    POSIX 1003.1
        These functions or macros are not defined by the ANSI/ISO C
        standard.  These function are specified in the document IEEE
        Standard Portable Operating System Interface for Computer
        Environments (IEEE Draft Standard 1003.1-1990).

    BIOS
        These functions access a service of the BIOS found in IBM Personal
        Computers and compatibles.  These functions should not be used if
        portability is a consideration.

    DOS
        These functions or macros are neither ANSI/ISO nor POSIX.  They
        perform a function related to DOS.  They may be found in other
        implementations of C for personal computers with DOS.  Use these
        functions with caution, if portability is a consideration.

    Intel
        These functions or macros are neither ANSI/ISO nor POSIX.  They
        performs a function related to the Intel x86 architecture.  They 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
        These functions are specific to OS/2.

    PC Graphics
        These functions are part of the PC graphics library.

    Windows
        These functions are specific to Microsoft Windows.

    WATCOM
        These functions or macros are neither ANSI/ISO nor POSIX.  They 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 (we do not include Netware
        or DOS/PM in this category).

    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, protected-mode extended DOS.

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

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

    Math
        This function is a math function.  Math functions are available on
        all systems.

    Netware
        This function is available on the 32-bit Novell Netware operating
        system.

    OS/2 1.x
        This function is available on IBM OS/2 1.x, a 16-bit protected-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 protected-mode DOS libraries (DOSPM*.LIB) for Phar
        Lap's 286|DOS-Extender (RUN286).

    OS/2-32
        This function is available on 32-bit IBM OS/2, a protected-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.

    Windows
        This function is available on 16-bit, protected-mode Windows 3.x.

    Win386
        This function is available on Microsoft Windows 3.x, using Watcom's
        Windows Extender for 32-bit protected-mode applications running on
        Intel 386 or upward compatible systems.

    Win32
        This function is available on Microsoft Windows NT and Windows 95,
        32-bit protected-mode systems for Intel 80386 and upwards compatible
        systems.  It may also be available for Windows 3.x using Win32s
        support.


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