| United States |
|
|
|
| Previous | Contents | Index |
Returns the hyperbolic sine of its argument.
#include <math.h>double sinh (double x);
x
A real number.
n The hyperbolic sine of the argument. HUGE_VAL Indicates that the argument is too large; errno is set to ERANGE.
Suspends the execution of the current process for at least the number of seconds indicated by its argument.
#include <unistd.h>unsigned int sleep (unsigned seconds); (_DECC_V4_SOURCE)
int sleep (unsigned seconds); (NOT _DECC_V4_SOURCE)
seconds
The number of seconds.
This function sleeps for the specified number of seconds, or until a signal is received, or until the process executes a call to SYS$WAKE.If a SIGALRM signal is generated, but blocked or ignored, the sleep function returns. For all other signals, a blocked or ignored signal does not cause sleep to return.
x The number of seconds that the process awoke early. 0 If the process slept the full number of seconds specified by seconds
Performs formatted output to a string in memory.
#include <stdio.h>int sprintf (char *str, const char *format_spec, ...);
str
The address of the string that will receive the formatted output. It is assumed that this string is large enough to hold the output.format_spec
A pointer to a character string that contains the format specification. For more information about format specifications and conversion characters, see Chapter 2....
Optional expressions whose resultant types correspond to conversion specifications given in the format specification.If no conversion specifications are given, you may omit the output sources. Otherwise, the function calls must have at least as many output sources as there are conversion specifications, and the conversion specifications must match the types of the output sources.
Conversion specifications are matched to output sources in left-to-right order. Excess output pointers, if any, are ignored.
A null character is automatically appended to the end of the output string. Consider the following example of a conversion specification:
#include <stdio.h> main() { int temp = 4, temp2 = 17; char s[80]; sprintf(s, "The answers are %d, and %d.", temp, temp2); }In this example, character string s has the following contents:
The answers are 4, and 17.For a complete description of the format specification and the output source, see Chapter 2.
x The number of characters placed in the output string, not including the final null character. Negative value Indicates an output error occurred. The function sets errno . For a list of errno values set by this function, see fprintf in this section.
Returns the square root of its argument.
#include <math.h>double sqrt (double x);
x
A real number.
The argument and the returned value are both objects of type double .
val The square root of x, if x is nonnegative. 0 Indicates that x is negative; errno is set to EDOM.
Initializes the pseudorandom number generator.
#include <math.h>void srand (unsigned int seed);
seed
An unsigned integer.
This function uses the argument as a seed for a new sequence of pseudorandom numbers to be returned by subsequent calls to rand .If rand is called before any calls to srand , the sequence of pseudorandom numbers is generated as if the seed were set to 1.
Initializes a 48-bit random number generator.
#include <stdlib.h>void srand48 (long int seed_val);
seed_val
The initialization value to begin randomization. Changing this value changes the randomization pattern.
This function initializes the random number generator. You can use this function in your program before calling the drand48 , lrand48 , or mrand48 functions. (Although it is not recommended practice, constant default initializer values are supplied automatically if you call drand48 , lrand48 , or mrand48 without calling an initialization function).
The function works by generating a sequence of 48-bit integer values, Xi, according to the linear congruential formula:
Xn+1 = (aXn+c)mod m n >= 0The argument m equals 248 , so 48-bit integer arithmetic is performed. Unless you invoke the lcong48 function, the multiplier value a and the addend value c are:
a = 5DEECE66D16 = 2736731631558 c = B16 = 138The initializer function srand48 sets the high-order 32 bits of Xi to the low-order 32 bits contained in its argument. The low-order 16 bits of Xi are set to the arbitrary value 330E _16 .
See also drand48 , lrand48 , and mrand48 in this section.
Generates pseudorandom numbers.
int srandom (unsigned seed);
seed
An initial seed value.
This function is a random number generator that has virtually the same calling sequence and initialization properties as the rand and srand function, but produce sequences that are more random.The srandom function initializes the current state with the initial seed value.
The srandom function, unlike the srand function, does not return the old seed because the amount of state information used is more than a single word.
See also rand , srand , and random in this section.
0 Indicates success. Initializes the state seed. --1 Indicates an error, further specified in the global errno .
Reads input from a character string in memory, interpreting it according to the format specification.
#include <stdio.h>int sscanf (const char *str, const char *format_spec, ...);
str
The address of the character string that provides the input text to sscanf .format_spec
A pointer to a character string that contains the format specification. For more information about format specifications and conversion characters, see Chapter 2....
Optional expressions whose resultant types correspond to conversion specifications given in the format specification.If no conversion specifications are given, you can omit the input pointers. Otherwise, the function calls must have at least as many input pointers as there are conversion specifications, and the conversion specifications must match the types of the input pointers.
Conversion specifications are matched to input sources in left-to-right order. Excess input pointers, if any, are ignored.
The following is an example of a conversion specification:
main () { char str[] = "4 17"; int temp, temp2; sscanf(str, "%d %d", &temp, &temp2); printf("The answers are %d and %d.", temp, temp2); }This example produces the following output:
$ RUN EXAMPLE The answers are 4 and 17.For a complete description of the format specification and the input pointers, see Chapter 2.
x The number of successfully matched and assigned input items. EOF Indicates that a read error occurred before any conversion.The function sets errno . For a list of the values set by this function, see fscanf in this section.
Allows you to specify the action to take when a particular signal is raised.
#include <signal.h>void (*ssignal (int sig, void (*func) (int, ...))) (int, ...);
sig
A number or mnemonic associated with a signal. The symbolic constants for signal values are defined in the <signal.h> header file (see Chapter 4).func
The action to take when the signal is raised, or the address of a function that is executed when the signal is raised.
This function is equivalent to the signal function except for the return value on error conditions.Since the signal function is defined by the ANSI C standard and the ssignal function is not, use signal for greater portability.
See Section 4.2 for more information on signal handling.
x The address of the function previously established as the action for the signal. The address may be the value SIG_DFL (0) or SIG_IGN (1). 0 Indicates errors. For this reason, there is no way to know whether a return status of 0 indicates failure, or whether it indicates that a previous action was SIG_DFL (0).
Deactivate the boldface attribute for the specified window. The standend function operates on the stdscr window.
#include <curses.h>int standend (void);
int wstandend (WINDOW *win);
win
A pointer to the window.
The standend and wstandend functions are equivalent to clrattr and wclrattr called with the attribute _BOLD.
OK Indicates success. ERR Indicates an error.
Activate the boldface attribute of the specified window. The standout function acts on the stdscr window.
#include <curses.h>int standout (void);
int wstandout (WINDOW *win);
win
A pointer to the window.
The standout and wstandout functions are equivalent to setattr and wsetattr called with the attribute _BOLD.
OK Indicates success. ERR Indicates an error.
Accesses information about the specified file.
#include <stat.h>Function Variants Compiling with the _DECC_V4_SOURCE and _VMS_V6_SOURCE feature-test macros defined enables a local-time-based entry point to this function that is equivalent to the behavior before OpenVMS Version 7.0.int stat (const char *file_spec, struct stat *buffer); (ISO POSIX-1)
int stat (const char *file_spec, struct stat *buffer, ...); (DEC C EXTENSION)
file_spec
A valid OpenVMS or UNIX style file specification (no wildcards). Read, write, or execute permission of the named file is not required, but you must be able to reach all directories listed in the file specification leading to the file. For more information about UNIX style file specifications, see Chapter 1.buffer
A pointer to a structure of type stat_t that is defined in the <stat.h> header file.The argument receives information about the particular file. The members of the structure pointed to by buffer are described as follows:
Member Type Definition st_dev dev_t Pointer to the physical device name st_ino[3] ino_t Three words to receive the file ID st_mode mode_t File "mode" (prot, dir,...) st_nlink nlink_t For UNIX system compatibility only st_uid uid_t Owner user ID st_gid gid_t Group member: from st_uid st_rdev dev_t UNIX system compatibility -- always 0 st_size off_t File size, in bytes st_atime time_t File access time; always the same as st_mtime st_mtime time_t Last modification time st_ctime time_t File creation time st_fab_rfm char Record format st_fab_rat char Record attributes st_fab_fsz char Fixed header size st_fab_mrs unsigned Record size The types dev_t , ino_t , off_t , mode_t , nlink_t , uid_t , gid_t , and time_t , are defined in the <stat.h> header file. However, when compiling for compatibility (/DEFINE=_DECC_V4_SOURCE), only dev_t , ino_t , and off_t are defined.
As of OpenVMS Version 7.0, times are given in seconds since the Epoch (00:00:00 GMT, January 1, 1970).
The st_mode structure member is the status information mode defined in the <stat.h> header file. The st_mode bits are described as follows:
Bits Constant Definition 0170000 S_IFMT Type of file 0040000 S_IFDIR Directory 0020000 S_IFCHR Character special 0060000 S_IFBLK Block special 0100000 S_IFREG Regular 0030000 S_IFMPC Multiplexed char special 0070000 S_IFMPB Multiplexed block special 0004000 S_ISUID Set user ID on execution 0002000 S_ISGID Set group ID on execution 0001000 S_ISVTX Save swapped text even after use 0000400 S_IREAD Read permission, owner 0000200 S_IWRITE Write permission, owner 0000100 S_IEXEC Execute/search permission, owner ...
An optional default file-name string in the form "dna=filespec".This is the only optional RMS keyword that can be specified for the stat function. See the description of the creat function for the full list of optional RMS keywords and their values.
This function does not work on remote network files.If the file is a record file, the st_size field includes carriage-control information. Consequently, the st_size value will not correspond to the number of characters that can be read from the file.
The physical device name string referred to by the st_dev member of the stat structure is overwritten by the next stat call.
0 Indicates success. --1 Indicates an error other than a privilege violation; errno is set to indicate the error. --2 Indicates a privilege violation.
| Previous | Next | Contents | Index |
|
