Intro(3G)

Intro -- introduction to general library routines

Synopsis

cc . . . -lgen

#include <libgen.h>

Description

This section contains manual pages for the routines in the libgen general-purpose library.

This library is not implemented as a shared object and is not automatically linked by the C compilation system. Specify -lgen on the cc(1) command line to link with this library.

Files

LIBDIRlibgen.a libgen library (archive)

Return values

For functions that return a floating-point value, if an error occurs, the value of errno will be one of the values represented by the manifest constants EDOM or ERANGE (defined in math.h). EDOM typically indicates a domain error: one of the input values was not in the domain of the function. ERANGE typically indicates a range error: the calculated result was either too big or too small to be represented by the data type returned by the function.

Functions that result in a range error typically return zero for underflow or a value that will compare equal to ±HUGE_VAL for overflow. HUGE_VAL is defined in math.h. On systems that support IEEE infinity, HUGE_VAL is infinity.

If the system supports IEEE NaN (not-a-number), functions that result in a domain error typically return NaN. Such functions may also raise one of the IEEE floating-point exceptions. On systems that do not support IEEE NaN, functions that result in a domain error typically return zero.

The error behavior for programs compiled with the -Xt (transitional) compilation mode is different (see cc(1)). In that case, these functions typically return zero instead of IEEE NaN for domain errors and a value that will compare equal to ±HUGE instead of ±HUGE_VAL for overflows. HUGE is defined in math.h.

Definitions

A character (except a multibyte character; see mbchar(3C)) is any bit pattern able to fit into a byte on the machine. The null character is a character with value 0, conventionally represented in the C language as \0. A character array is a sequence of characters. A null-terminated character array (a ``string'') is a sequence of characters, the last of which is the null character. The null string is a character array containing only the terminating null character. A NULL pointer is the value that is obtained by casting 0 into a pointer. C guarantees that this value will not match that of any legitimate pointer, so many functions that return pointers return NULL to indicate an error. The macro NULL is defined in stdio.h. Types of the form size_t are defined in the appropriate header files.

References

cc(1)

Standards conformance

The following are conformant with X/Open Portability Guide, Issue 4, Version 2 (UNIX95): advance(3G), basename(3G), closelog(3G), compile(3G), dirname(3G), encrypt(3G), endutxent(3G), getutxent(3G), openlog(3G), pututxline(3G), regcmp(3G), setkey(3G), setlogmask(3G), setutxent(3G), step(3G)

The remaining routines are not part of any currently supported standard. They are an extension of AT&T System V provided by the Santa Cruz Operation.