Functions and variables in alphabetical order

This chapter contains detailed descriptions, in alphabetical order, of the functions, macros and external variables that are supported by the C runtime system in both the POSIX subsystem as well as in BS2000.

Format of entries

Each description begins with a title containing the symbolic name and some keywords to describe the functionality and is always followed by the same subsections:

Syntax	Syntax of the function call or variable declaration and of the header file in which the relevant interface is defined or declared. A syntax line may be additionally identified as follows: Optional An include statement identified as optional need not be specified in newly created source code. Nor need it be deleted from existing source code. The end of each such section is indicated by the end marker (End). C11 A declaration marked in this way is only defined in the header-file for compilation with C/C++ version >= V4.0A and language-mode X11 or C++ 2017. The end of each such section is indicated by the end marker (End). not C11 A declaration marked in this way is not defined in the header-file for compilation with C/C++ version >= V4.0A and language-mode X11 or C++ 2017. The end of each such section is indicated by the end marker (End). CRTE111A30 A declaration marked in this way is only contained in the include file of CRTE version V11.1A30 or higher. A CRTE version V11.1A30 or higher and a POSIX-BC correction status A47 or higher are required to run the function.  The end of each such section is indicated by the end marker (End).
Description	Describes the functionality of the respective function, macro or external variable and explains the arguments to be specified.
Return val.	Lists and describes the possible return values of a function. Some functions do not have a return value. In such cases and when describing external variables, the "Return value" section is omitted.
Errors	Lists and describes the error codes stored in the external variable errno in the case of an invalid function call or an execution error. Some functions do not store an error code in errno in the event of an error. In such cases and when describing external variables, the "Errors" section is omitted.
Notes	Typically includes explanations of concepts, information on interaction with other functions, and/or tips concerning application usage. This section may be omitted in some cases.
See also	Contains cross-references to function descriptions, header files, sections in the chapters on concepts and other manuals.

Text segments that are not specially identified describe XPG4-conformant implementations. Extensions and deviations with respect to the Standard are indicated by the following markers:

BS2000
Information on extensions of the C runtime system describing functionality in connection with access to DMS and C runtime versions up to V2.1C (i.e. BS2000 functionality). The end of each such section is indicated by the end marker. (End)
If a function is a BS2000-specific extension, it is marked in the title as such: (BS2000).

Extension
Information on extensions of the C runtime system. The end of each such section is indicated by the end marker (End).
If a function is an extension, as supported on many UNIX systems, it is marked as such: (extension).

Restriction
Information on current restrictions of the C runtime system as opposed to the XPG4 standard. The end of each such section is indicated by the end marker. (End)