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.If any of these routines fail, the ICCfailure variable will identify the system call that failed.HISTORYWritten by Rich $alz (rsalz@uunet.uu.net) for InterNetNews.SEE ALSOctlinnd(8), innd(8), libinn(3). isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit957insque, remqueinsque, remque Insert/Remove an item from a queueSYNOPSIS#includevoid insque(struct qelem * elem, struct qelem * prev);void remque(struct qelem*elem);DESCRIPTIONinsque() and remque() are functions for manipulating queues made from doubly linked lists.Each element in this list is oftype struct qelem.The qelem structure is defined asstruct qelem {struct qelem *q_forw;struct qelem *q_back;char q_data[1];};insque() inserts the element pointed to by elem immediately after the element pointed to by prev, which must not be NULL.remque() removes the element pointed to by elem from the doubly linked list.CONFORMS TOSVR4BUGSThe q_data field is sometimes defined to be of type char *, and under Solaris 2.x, it doesn t appear to exist at all.The location of the prototypes for these functions differs among several versions of UNIX.Some systems place them in, others in.Linux places them in because that seems to make the most sense.Some versions of UNIX (such as HP-UX 10.x) do not define a struct qelem but rather have the arguments to insque() andremque() be of type void *.GNU, 30 October 1996isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph,islower, isprint, ispunct, isspace, isupper, isxdigitisalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigitCharacter classification routinesSYNOPSIS#includeint isalnum (int c);int isalpha (int c);int isascii (int c);int isblank (int c);int iscntrl (int c);int isdigit (int c);int isgraph (int c);int islower (int c);int isprint (int c);int ispunct (int c); Part III: Library Functions958int isspace (int c);int isupper (int c);int isxdigit (int c);DESCRIPTIONThese functions check whether c, which must have the value of an unsigned char or EOF, falls into a certain character classaccording to the current locale:isalnum() Checks for an alphanumeric character; it is equivalent to (isalpha(c) || isdigit(c)).isalpha() Checks for an alphabetic character; in the standard C locale, it is equivalent to (isupper(c) ||islower(c)).In some locales, there may be additional characters for which isalpha() is trueletters that are neither uppercase nor lowercase.isascii() Checks whether c is a 7-bit unsigned char value that fits into the ASCII character set.Thisfunction is a BSD extension and is also an SVID extension.isblank() Checks for a blank character; that is, a space or a tab.This function is a GNU extension.iscntrl() Checks for a control character.isdigit() Checks for a digit (0 through 9).isgraph() Checks for any printable character except space.islower() Checks for a lowercase character.isprint() Checks for any printable character, including space.ispunct() Checks for any printable character that is not a space or an alphanumeric character.isspace() Checks for whitespace characters.They are space, form-feed ( \f ), newline ( \n ), carriagereturn ( \r ), horizontal tab ( \t ), and vertical tab ( \v ).isupper() Checks for an uppercase letter.isxdigit() Checks for a hexadecimal digit (that is, one of 0 1 2 3 4 5 6 7 8 9 0 a b c d e f A B C D E F).RETURN VALUEThe values returned are nonzero if the character c falls into the tested class, and 0 if it does not.CONFORMS TOANSI C, BSD 4.3.isascii() is a BSD extension and is also an SVID extension.isblank() is a GNU extension.BUGSThe details of what characters belong in which class depend on the current locale.For example, isupper() will not recognizean A with an umlaut (Ä) as an uppercase letter in the default C locale.SEE ALSOtolower(3), toupper(3), setlocale(3), ascii(7), locale(7)GNU, 2 September 1995isattyisatty Tests whether this descriptor refers to a terminalSYNOPSIS#includeint isatty (int desc );DESCRIPTIONisatty returns 1 if desc is an open descriptor connected to a terminal, and 0 otherwise. j0, j1, jn, y0, y1, yn959CONFORMS TOSVID, AT&T, X/OPEN, BSD 4.3SEE ALSOfstat(2), ttyname(3)Linux, 20 April 1995isinf, isnan, finiteisinf, isnan, finite Test for infinity or not-a-number (NaN)SYNOPSIS#includeint isinf(double value);int isnan(double value);int finite(double value);DESCRIPTIONThe isinf() function returns 1 if value represents negative infinity, 1 if value represents positive infinity, and 0 otherwise.The isnan() function returns a nonzero value if value is not-a-number (NaN), and 0 otherwise.The finite() function returns a nonzero value if value is finite or is not a not-a-number (NaN) value, and 0 otherwise.CONFORMS TOBSD 4
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