HP C/iX Library Reference Manual (30026-90004)

4 Chapter1

Introduction to the HP C/iX Library

Organization of the HP C/iX Library

The HP C/iX library consists of several ﬁles that can be divided into three groups:

standard library functions, mathematical library functions, and library functions available

only on HP 3000 Series 900 computers.

If you are developing POSIX applications on MPE/iX, you will be using the POSIX/iX

library. This library is separate from the HP C/iX library and is organized differently. The

POSIX/iX library is described in the MPE/iX Developer's Kit Reference Manual.

The Standard Library

The standard library consists of the input/output functions, the general utility functions,

and the program startup routines. All C programs must link in the standard library

because it contains the startup routines necessary for program execution. Failure to link in

this library results in a linker or loader error.

The standard C library functions are provided in three different forms: a relocatable

library (LIBC.LIB.SYS), an executable library (XL.PUB.SYS), and a relocatable library that

is suitable for adding to an executable library that you build (LIBCXL.LIB.SYS).

Each form of the library is intended for different uses. The relocatable form

(LIBC.LIB.SYS) is for programmers who want the HP Link Editor/iX to bind copies of

library functions to the application program at link time. This reduces the amount of

dynamic binding that must be done at run time. However, this makes less efﬁcient use of

memory space because each application duplicates the library functions that it uses.

The executable forms of the library are placed into shared libraries that can be accessed

when applications written in C are executed. System memory usage decreases when C

programs access the shared library. Only one copy of each function is loaded into the

computer's main memory. For example, if several applications use printf, only one copy of

the actual printf executable code is loaded into memory. All applications share the same

copy.

The ﬁles that contain the standard library are listed in <Undeﬁned Cross-Reference>:

Table 1-1. Standard Library Files

File Description

XL.PUB.SYS The executable library (XL) form of the standard library, including

executable libraries from other subsystems and languages.

LIBCINIT.LIB.SYS The code necessary to initialize the XL form of standard library.

LIBC.LIB.SYS The relocatable library (RL) form of the standard library functions.

LIBCANSI.LIB.SYS The relocatable library that should be linked along with LIBCINIT or

LIBC if conformance to ANSI C is desired.

LIBCRAND.LIB.SYS The random number related functions, rand and srand, in RL form.