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Initializes the pseudorandom-number generator random .
int srandom (unsigned seed);
seed
An initial seed value.
The srandom function uses the argument as a seed for a new sequence of pseudorandom numbers to be returned by subsequent calls to random . This function has virtually the same calling sequence and initialization properties as the 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 , random , setstate , and initstate .
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 .
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.
The ssignal 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 the stat 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, ...); (HP C EXTENSION)
Compiling with the _USE_STD_STAT feature-test macro defined enables a variant of the stat function that uses an X/Open standard-compliant definition of the stat structure. The _USE_STD_STAT feature-test macro is mutually exclusive with the _DECC_V4_SOURCE and _VMS_V6_SOURCE macros.
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 . For convenience, a typedef stat_t is defined as struct stat in the <stat.h> header file.This argument receives information about the particular file. The members of the structure pointed to by buffer are described in the Description section.
...
An optional default file-name string.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.
When the _USE_STD_STAT feature-test macro is not enabled, the legacy stat structure is used. When _USE_STD_STAT is enabled, the X/Open standard-compliant stat structure is used.Legacy stat Structure
With the _USE_STD_STAT feature-test macro defined to DISABLE, the following legacy stat structure is used:
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. For st_size to report a correct value, you need to flush both the C RTL and RMS buffers. 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.
The off_t data type is either a 32-bit or 64-bit integer. The 64-bit interface allows for file sizes greater than 2 GB, and can be selected at compile time by defining the _LARGEFILE feature-test macro as follows:
CC/DEFINE=_LARGEFILEAs 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 The stat 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.
Also be aware that for st_size to report a correct value, you need to flush both the C RTL and RMS buffers.
Standard-Compliant stat Structure
With OpenVMS Version 8.2, the _USE_STD_STAT feature-test macro and standard-compliant stat structure are introduced in support of UNIX compatibility.
With _USE_STD_STAT defined to ENABLE, you get the following behavior:
- Old struct stat definitions
Old definitions of struct stat are obsolete. You must recompile your applications to access the new features. Existing applications will continue to access the old definitions and functions unless they are recompiled to use the new features.- Function variants
Calls to stat , fstat , lstat , and ftw accept pointers to structures of the new type. Calls to these functions are mapped to the new library entries __std_stat , __std_fstat , __std_lstat , and __std_ftw , respectively.- Compatibilities with other feature macros
_DECC_V4_SOURCE source-code compatibility is not supported. You must not enable _DECC_V4_SOURCE and _USE_STD_STAT at the same time.
_VMS_V6_SOURCE binary compatibility is not supported. You must not enable _VMS_V6_SOURCE and _USE_STD_STAT at the same time. As a result, only UTC (rather than local-time) is supported for the time_t fields.- Type changes
The following type changes are in effect:
- 32-bit gid type gid_t is used. _DECC_SHORT_GID_T is unsupported.
- _LARGEFILE offsets are used. off_t is forced to 64 bits.
- Type ino_t , representing the file number, is an unsigned int quadword (64 bits). Previously, it was an unsigned short .
- Type dev_t , representing the device id, is an unsigned int quadword (64 bits). Previously, it was a 32-bit character pointer. The new type is standard because it is arithmetic.
- Types blksize_t and blkcnt_t are added and defined as unsigned int quadwords (64 bits).
- Structure member Changes
- Two members are added to struct stat :
blksize_t st_blksize; blkcnt_t st_blocks;
According to the X/Open standard, st_blksize is the filesystem-specific preferred I/O blocksize for this file. On OpenVMS systems, st_blksize is set to the device buffer size multiplied by the disk cluster size. st_blocks is set to the allocated size of the file, in blocks. The blocksize used to calculate st_blocks is not necessarily the same as st_blksize and, in most cases, will not be the same.- In struct stat , member st_ino is of type ino_t . In previous C RTL versions, it was of type ino_t [3] (array of 3 ino_t ). Since ino_t has changed from a word to a quadword, the size of this member has increased by one word. The principal significance of this change is that it makes st_ino a scalar, which is how most open source applications define it.
- The new definition of ino_t also affects applications that include the <dirent.h> header file. In struct dirent , member d_ino changes in the same way as the st_ino member of struct stat in <stat.h> .
- Several macros that are not part of any standard were introduced in <stat.h> to facilitate access to the constituent parts of ino_t values:
S_INO_NUM(ino), S_INO_SEQ(ino), and S_INO_RVN(ino) return the FILES-11 file number, sequence number, and relative volume number of ino, respectively, as unsigned short s.
S_INO_RVN_RVN(ino) returns the byte of the RVN field containing the relative volume number;
S_INO_RVN_NMX(ino) returns the byte of the RVN field containing the file number extension.
Although individual components can be broken out like this, they are not part of the X/Open standard and should not be relied on in portable applications.- Semantic changes
Values of type dev_t are now unique for each device across clusters. An algorithm based on device name and allocation class or SCSSYSTEMID (for single-pathed devices) calculates the device id value having these characteristics, an X/Open standard requirement. Typically, the combination of file number and device id uniquely identifies a file in a cluster.
This change affects stat structure members st_dev and st_rdev . For compatibility with previous releases, st_rdev is set to either 0 or st_dev .
Note (ALPHA, I64)
On OpenVMS Alpha and I64 systems, the stat , fstat , utime , and utimes functions have been enhanced to take advantage of the new file-system support for POSIX compliant file timestamps.
This support is available only on ODS-5 devices on OpenVMS Alpha systems beginning with a version of OpenVMS Alpha after Version 7.3.
Before this change, the stat and fstat functions were setting the values of the st_ctime , st_mtime , and st_atime fields based on the following file attributes:st_ctime - ATR$C_CREDATE (file creation time)
st_mtime - ATR$C_REVDATE (file revision time)
st_atime - was always set to st_mtime because no support for file access time was available
Also, for the file-modification time, utime and utimes were modifying the ATR$C_REVDATE file attribute, and ignoring the file-access-time argument.
After the change, for a file on an ODS-5 device, the stat and fstat functions set the values of the st_ctime , st_mtime , and st_atime fields based on the following new file attributes:st_ctime - ATR$C_ATTDATE (last attribute modification time)
st_mtime - ATR$C_MODDATE (last data modification time)
st_atime - ATR$C_ACCDATE (last access time)
If ATR$C_ACCDATE is zero, as on an ODS-2 device, the stat and fstat functions set st_atime to st_mtime .
For the file-modification time, the utime and utimes functions modify both the ATR$C_REVDATE and ATR$C_MODDATE file attributes. For the file-access time, these functions modify the ATR$C_ACCDATE file attribute. Setting the ATR$C_MODDATE and ATR$C_ACCDATE file attributes on an ODS-2 device has no effect.
For compatibility, the old behavior of stat , fstat , utime , and utimes remains the default, regardless of the kind of device.
The new behavior must be explicitly enabled by defining the DECC$EFS_FILE_TIMESTAMPS logical name to ENABLE before invoking the application. Setting this logical does not affect the behavior of stat , fstat , utime , and utimes for files on an ODS-2 device.
0 Indicates success. - 1 Indicates an error other than a privilege violation; errno is set to indicate the error. - 2 Indicates a privilege violation.
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