getwchar

Reads a single wide character from the standard input (stdin).

Format

#include <wchar.h>

wint_t getwchar (void);

Description

The getwchar function is identical to fgetwc(stdin) .

Return Values

x	The next character from stdin, converted to wint_t .
WEOF	Indicates the end-of-file or an error. If an error occurs, the function sets errno . For a list of the values set by this function, see fgetwc in this section.

getyx

Puts the (y,x) coordinates of the current cursor position on win in the variables y and x.

Format

#include <curses.h>

getyx (WINDOW *win, int y, int x);

Arguments

win

Must be a pointer to the window.

y

Must be a valid lvalue.

x

Must be a valid lvalue.

gmtime, gmtime_r

Converts time units to the broken-down UTC time.

Format

#include <time.h>

struct tm *gmtime (const time_t *timer);

struct tm *gmtime_r (const time_t *timer, struct tm *result); (ISO POSIX-1)

Arguments

timer

Points to a variable that specifies a time value in seconds since the Epoch.

result

A pointer to a tm structure where the result is stored.

The tm structure is defined in the <time.h> header, and is also shown in Table REF-4 in the description of localtime .

Description

The gmtime and gmtime_r functions convert the time (in seconds since the Epoch) pointed to by timer into a broken-down time, expressed as Coordinated Universal Time (UTC), and store it in a tm structure.

The difference between the gmtime_r and gmtime functions is that the former puts the result into a user-specified tm structure where the result is stored. The latter puts the result into thread-specific static memory allocated by the Compaq C RTL, and which is overwritten by subsequent calls to gmtime ; you must make a copy if you want to save it.

On success, gmtime returns a pointer to the tm structure; gmtime_r returns its second argument. On failure, these functions return the NULL pointer.

Note Generally speaking, UTC-based time functions can affect in-memory time-zone information, which is process-wide data. However, if the system time zone remains the same during the execution of the application (which is the common case) and the cache of timezone files is enabled (which is the default), then the _r variant of the time functions asctime_r , ctime_r , gmtime_r and localtime_r , is both thread-safe and AST-reentrant. If, however, the system time zone can change during the execution of the application or the cache of timezone files is not enabled, then both variants of the UTC-based time functions belong to the third class of functions, which are neither thread-safe nor AST-reentrant.

Return Values

x	Pointer to a tm structure.
NULL	Indicates an error; errno is set to one of the following values: EINVAL -- The timer argument is NULL.

gsignal

Generates a specified software signal, which invokes the action routine established by a signal , ssignal , or sigvec function.

Format

#include <signal.h>

int gsignal (int sig [, int sigcode]);

Arguments

sig

The signal to be generated.

sigcode

An optional signal code. For example, signal SIGFPE---the arithmetic trap signal---has 10 different codes, each representing a different type of arithmetic trap.

The signal codes can be represented by mnemonics or numbers. The arithmetic trap codes are represented by the numbers 1 to 10, but the SIGILL codes are represented by the numbers 0 to 2. The code values are defined in the <signal.h> header file. See Tables 4-4 and 4-5 for a list of signal mnemonics, codes, and corresponding OpenVMS exceptions.

Description

Calling this function has one of the following results:

• If gsignal specifies a sig argument that is outside the range defined in the <signal.h> header file, then gsignal returns 0 and sets errno to EINVAL.
• If signal , ssignal , or sigvec establishes SIG_DFL (default action) for the signal, then gsignal does not return. The image is exited with the OpenVMS error code corresponding to the signal.
• If signal , ssignal , or sigvec establishes SIG_IGN (ignore signal) as the action for the signal, then gsignal returns its argument, sig.
• signal , ssignal , or sigvec must be used to establish an action routine for the signal. That function is called and its return value is returned by gsignal .

See also raise , signal , ssignal , and sigvec in this section.

See Chapter 4 for more information.

Return Values

0	Indicates a sig argument that is outside the range defined in the <signal.h> header file; errno is set to EINVAL.
sig	Indicates that SIG_IGN (ignore signal) has been established as the action for the signal.
x	Indicates that signal , ssignal , or sigvec has established an action function for the signal. That function is called, and its return value is returned by gsignal .

hypot

Returns the length of the hypotenuse of a right triangle.

Format

#include <math.h>

double hypot (double x, double y);

float hypotf (float x, float y); (ALPHA ONLY)

long double hypotl (long double x, long double y); (ALPHA ONLY)

Arguments

x

A real value.

y

A real value.

Description

The hypot functions return the length of the hypotenuse of a right triangle, where x and y represent the perpendicular sides of the triangle. The length is calculated as:

sqrt(x2 + y2)

On overflow, the return value is undefined, and errno is set to ERANGE.

Return Values

x	The length of the hypotenuse.
HUGE_VAL	Overflow occurred; errno is set to ERANGE.
0	Underflow occurred; errno is set to ERANGE.
NaN	x or y is NaN; errno is set to EDOM.

iconv

Converts characters coded in one codeset to characters coded in another codeset.

Format

#include <iconv.h>

size_t iconv (iconv_t cd, char **inbuf, size_t *inbytesleft, char **outbuf, size_t *outbytesleft);

Arguments

cd

A conversion descriptor. This is returned by a successful call to iconv_open .

inbuf

A pointer to a variable that points to the first character in the input buffer.

inbytesleft

Initially, this argument is a pointer to a variable that indicates the number of bytes to the end of the input buffer (inbuf). When the conversion is completed, the variable indicates the number of bytes in inbuf not converted.

outbuf

A pointer to a variable that points to the first available byte in the output buffer. The output buffer contains the converted characters.

outbytesleft

Initially, this argument is a pointer to a variable that indicates the number of bytes to the end of the output buffer (outbuf). When the conversion is completed, the variable indicates the number of bytes left in outbuf.

Description

This function converts characters in the buffer pointed to by inbuf to characters in another code set. The resulting characters are stored in the buffer pointed to by outbuf. The conversion type is specified by the conversion descriptor cd. This descriptor is returned from a successful call to iconv_open .

If an invalid character is found in the input buffer, the conversion stops after the last successful conversion. The variable pointed to by inbytesleft is updated to reflect the number of bytes in the input buffer that are not converted. The variable pointed to by outbytesleft is updated to reflect the number of bytes remaining in the output buffer.

Return Values

x	Number of non-identical conversions performed. Indicates successful conversion. In most cases 0 is returned.
( size_t ) --1	Indicates an error condition. The function sets errno to one of the following: EBADF -- The cd argument is not a valid conversion descriptor. EILSEQ -- The conversion stops when an invalid character detected. E2BIG -- The conversion stops because of insufficient space in the output buffer. EINVAL -- The conversion stops because of an incomplete character at the end of the input buffer.

iconv_close

Deallocates a specified conversion descriptor and the resources allocated to the descriptor.

Format

#include <iconv.h>

int iconv_close (iconv_t cd);

Arguments

cd

The conversion descriptor to be deallocated. A conversion descriptor is returned by a successful call to iconv_open .

Return Values

0	Indicates that the conversion descriptor was successfully deallocated.
--1	Indicates an error occurred. The function sets errno to one of the following: EBADF -- The cd argument is not a valid conversion descriptor. EVMSERR -- Non-translatable VMS error occur. vaxc$errno contains the VMS error code.

iconv_open

Allocates a conversion descriptor for a specified codeset conversion.

Format

#include <iconv.h>

iconv_t iconv_open (const char *tocode, const char *fromcode);

Arguments

tocode

The name of the codeset to which characters are converted.

fromcode

The name of the source codeset. See Chapter 10 for information on obtaining a list of currently available codesets or for details on adding new codesets.

Return Values

x

A conversion descriptor. Indicates the call was successful. This descriptor is used in subsequent calls to iconv

(iconv_t) --1

Indicates an error occurred. The function sets errno to one of the following: EMFILE -- The process does not have enough I/O channels to open a file. ENOMEM -- Insufficient space is available. EINVAL -- The conversion specified by fromcode and tocode is not supported. EVMSERR -- Nontranslatable VMS error occur. vaxc$errno contains the VMS error code. A value of SS$_BADCHKSUM in vaxc$errno indicates that a conversion table file was found, but its contents is corrupted. A value of SS$_IDMISMATCH in vaxc$errno indicates that the conversion table file version does not match the version of the C Run-Time Library.

Example

#include <stdio.h> #include <iconv.h> #include <errno.h> int main() { /* Declare variables to be used */ char fromcodeset[30]; char tocodeset[30]; int iconv_opened; iconv_t iconv_struct; /* Iconv descriptor */ /* Initialize variables */ sprintf(fromcodeset, "DECHANYU"); sprintf(tocodeset, "EUCTW"); iconv_opened = FALSE; /* Attempt to create a conversion descriptor for the */ /* codesets specified. If the return value from */ /* iconv_open is -1 then an error has occurred. */ /* Check the value of errno. */ if ((iconv_struct = iconv_open(tocodeset, fromcodeset)) == (iconv_t) - 1) { /* Check the value of errno */ switch (errno) { case EMFILE: case ENFILE: printf("Too many iconv conversion files open\n"); break; case ENOMEM: printf("Not enough memory\n"); break; case EINVAL: printf("Unsupported conversion\n"); break; default: printf("Unexpected error from iconv_open\n"); break; } } else /* Successfully allocated a conversion descriptor */ iconv_opened = TRUE; /* Was a conversion descriptor allocated */ if (iconv_opened) { /* Attempt to deallocate the conversion descriptor. */ /* If iconv_close returns -1 then an error has */ /* occurred. */ if (iconv_close(iconv_struct) == -1) { /* An error occurred. Check the value of errno */ switch (errno) { case EBADF: printf("Conversion descriptor is invalid\n"); break; default: printf("Unexpected error from iconv_close\n"); break; } } } return (EXIT_FAILURE); }

[w]inch

Return the character at the current cursor position on the specified window without making changes to the window. The inch function acts on the stdscr window.

Format

#include <curses.h>

char inch();

char winch (WINDOW *win);

Argument

win

A pointer to the window.

Return Values

x	The returned character.
ERR	Indicates an input error.

index

Search for a character in a string.

Format

#include <strings.h>

char *index (const char *s, int c);

Arguments

s

The string to search.

c

The character to search for.

Description

The index function is identical to the strchr function, and is provided for compatibility with some UNIX implementations.

initscr

Initializes the terminal-type data and all screen functions. You must call initscr before using any of the curses functions.

Format

#include <curses.h>

void initscr (void);

Description

The OpenVMS Curses version of this function clears the screen before doing the initialization. The BSD-based Curses version does not.

initstate

Initializes random number generators.

Format

#include <stdlib.h>

char *initstate (unsigned int seed, char *state, int size);

Arguments

seed

An initial seed value.

state

Pointer to an array of state information.

size

The size of the state information array.

Description

This function initializes random number generators. It lets you initialize for future use, a state array passed as an argument. The size in bytes of the state array is used by the initstate function to decide how sophisticated a random number generator to use; the larger the state array, the more random the numbers.

Values for the amount of state information are 8, 32, 64, 128, and 256 bytes. Amounts less than 8 bytes generate an error, while other amounts are rounded down to the nearest known value.

The seed argument specifies a starting point for the random number sequence and provides for restarting at the same point. The initstate function returns a pointer to the previous state information array.

Once you initialize a state, the setstate function allows rapid switching between states. The array defined by the state argument is used for further random number generation until the initstate function is called or the setstate function is called again. The setstate function returns a pointer to the previous state array.

After initialization, you can restart a state array at a different point in one of two ways:

• Use the initstate function with the desired seed argument, state array, and size of the array.
• Use the setstate function with the desired state, followed by the srandom function with the desired seed. The advantage of using both functions is that you do not have to save the state array size once you initialize it.

See also setstate , srandom , and random , in this section.

Return Values

x	A pointer to the previous state array information.
0	Indicates an error. Call made with less than 8 bytes of state information. Further specified in the global errno .

[w]insch

Insert a character at the current cursor position in the specified window. The insch function acts on the stdscr window.

Format

#include <curses.h>

int insch (char ch);

int winsch (WINDOW *win, char ch);

Arguments

win

A pointer to the window.

ch

The character to be inserted.

Description

After the character is inserted, each character on the line shifts to the right, and the last character in the line is deleted. For more information, see the scrollok function in this section.

Return Values

OK	Indicates success.
ERR	Indicates that the function makes the screen scroll illegally.