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len = strlen(name); dir_pointer = opendir("."); for (dp = readdir(dir_pointer); dp != NULL; dp = readdir(dir_pointer)) if (dp->d_namlen == len && !strcmp(dp->d_name, name)) { closedir(dir_pointer); return FOUND; } closedir(dir_pointer); return NOT_FOUND; |
0 Indicates success. --1 Indicates an error and is further specified in the global errno .
Deactivate the video display attribute attr within the window. The clrattr function acts on the stdscr window.
#include <curses.h>int clrattr (int attr);
int wclrattr (WINDOW *win, int attr);
win
A pointer to the window.attr
Video display attributes that can be blinking, boldface, reverse video, and underlining; they are represented by the defined constants _BLINK, _BOLD, _REVERSE, and _UNDERLINE. To clear multiple attributes, separate them with a bitwise OR operator (|) as follows:
clrattr(_BLINK | _UNDERLINE);
These functions are specific to DEC C for OpenVMS Systems and are not portable.
OK Indicates success. ERR Indicates an error.
Erase the contents of the window from the current position of the cursor to the bottom of the window. The clrtobot function acts on the stdscr window.
#include <curses.h>int clrtobot();
int wclrtobot (WINDOW *win);
win
A pointer to the window.
OK Indicates success. ERR Indicates an error.
Erase the contents of the window from the current cursor position to the end of the line on the specified window. The clrtoeol function acts on the stdscr window.
#include <curses.h>int clrtoeol();
int wclrtoeol (WINDOW *win);
win
A pointer to the window.
OK Indicates success. ERR Indicates an error.
Determines the current value of a specified system variable defined by a string value.
#include <unistd.h>size_t confstr (int name, char *buf, size_t len);
name
The system variable setting. Valid values for the name argument are the _CS_X names defined in the <unistd.h> header file.buf
Pointer to the buffer where the confstr function copies the name value.len
The size of the buffer storing the name value.
This function allows an application to determine the current setting of certain system parameters, limits, or options that are defined by a string value. The function is mainly used by applications to find the system default value for the path environment variable.If the following conditions are true, then the confstr function copies that value into a len-byte buffer pointed to by buf:
- The len argument is not 0 (zero).
- The name argument has a system-defined value.
- The buf argument is not a NULL pointer.
If the returned string is longer than len bytes, including the terminating null, then the confstr function truncates the string to len --1 bytes and adds a terminating null to the result. The application can detect that the string was truncated by comparing the value returned by the confstr function with the value of the len argument.
The <limits.h> header file contains system-defined limits. The <unistd.h> header file contains system-defined environmental variables.
To find out how big a buffer is needed to store the string value of name, enter:
confstr(_CS_PATH, NULL, (size_t) 0)The confstr function returns the size of the buffer necessary.
0 Indicates an error. When the specified name value:
- Is invalid, errno is set to EINVAL.
- Does not have a system-defined value, errno is not set.
n The size of the buffer needed to hold the value.
- When the value of the name argument is system-defined, confstr returns the size of the buffer needed to hold the entire value. If this return value is greater than the len value, the string returned as the buf value is truncated.
- When the value of the len argument is set to 0 or the buf value is NULL, confstr returns the size of the buffer needed to hold the entire system-defined value. The string value is not copied.
Returns the cosine of its radian argument.
#include <math.h>double cos (double x);
x
A radian expressed as a real value.
x The cosine of the argument. HUGE_VAL Indicates that the argument is too large; errno is set to ERANGE.
Returns the hyperbolic cosine of its argument.
#include <math.h>double cosh (double x);
x
A real value.
x The hyperbolic cosine of the argument. HUGE_VAL Indicates that the argument is too large; errno is set to ERANGE.
Returns the cotangent of its radian argument.
#include <math.h>double cot (double x);
x
A radian expressed as a real number.
x The cotangent of the argument. HUGE_VAL Indicates that the argument is zero; errno is set to ERANGE.
Creates a new file.
#include <fcntl.h>int creat (const char *file_spec, mode_t mode);
(ISO POSIX-1) int creat (const char *file_spec, mode_t mode, ...);
(DEC C EXTENSION)
file_spec
A null-terminated string containing any valid file specification.mode
An unsigned value that specifies the file-protection mode. The compiler performs a bitwise AND operation on the mode and the complement of the current protection mode.You can construct modes by using the bitwise OR operator (|) to create mode combinations. The modes are as follows:
0400 OWNER:READ 0200 OWNER:WRITE 0100 OWNER:EXECUTE 0040 GROUP:READ 0020 GROUP:WRITE 0010 GROUP:EXECUTE 0004 WORLD:READ 0002 WORLD:WRITE 0001 WORLD:EXECUTE The system is given the same privileges as the owner. A WRITE privilege implies a DELETE privilege.
Note
To create files with OpenVMS RMS default protections using the UNIX system-call functions umask , mkdir , creat , and open , call mkdir , creat , and open with a file-protection mode argument of 0777 in a program that never specifically calls umask . These default protections include correctly establishing protections based on ACLs, previous versions of files, and so on.
In programs that do vfork / exec calls, the new process image inherits whether umask has ever been called or not from the calling process image. The umask setting and whether the umask function has ever been called are both inherited attributes....
An optional argument list of character strings of the following form:
"keyword = value",...,"keyword= value"
Or in the case of "acc" or "err", this form:
"keyword"
Here, keyword is an RMS field in the file access block (FAB) or record access block (RAB); value is valid for assignment to that field. Some fields permit you to specify more than one value. In these cases, the values are separated by commas.
The RMS callback keywords "acc" and "err" are the only keywords that do not take values. Instead, they are followed by a pointer to the callback routine to be used, followed by a pointer to a user-specified value to be used as the first argument of the callback routine. For example, to set up an access callback routine called acc_callback whose first argument is a pointer to the integer variable first_arg in a call to open , you can use the following statement:
open("file.dat", O_RDONLY, 0 ,"acc", acc_callback, &first_arg)The second and third arguments to the callback routine must be pointers to a FAB and RAB, respectively, and the routine must have a return type of int . If the callback retruns a value less than 0, the open , creat , or fopen fails. The error callback can correct the error condition and return a status greater than or equal to 0 to continue the creat call. Assuming the previous open statement, the function prototype for acc_callback would be similar to the following statement:
#include <rms.h> int acc_callback(int *first_arg, struct FAB *fab, struct RAB *rab);FAB and RAB are defined in the <rms.h> header file, and the actual pointers passed to the routine are pointers to the RAB and FAB being used to open the file file.dat.
If an access callback routine is established, then it will be called in the open-type routine immediately before the call to the RMS function sys$create or sys$open. If an error callback routine is established and an error status is returned from the sys$create or sys$open function, then the callback routine will be invoked immediately after the status is checked and the error value is discovered.
Note
Any manipulation of the RAB or FAB in a callback function could lead to serious problems in later calls to the DEC C RTL I/O functions.Table REF-3 describes the RMS keywords and values.
Table REF-3 RMS Valid Keywords and Values Keyword Value Description "acc" callback Access callback routine. "alq = n" decimal Allocation quantity. "bls = n" decimal Block size. "ctx = bin" string No translation of '\n' to the terminal. Use this for writing binary data to files. "ctx=cvt" string Negates a previous setting of "ctx=nocvt". This is the default. "ctx = nocvt" string No conversion of Fortran carriage-control bytes. "ctx = rec" string Force record mode access. "ctx = stm" string Force stream mode access. "ctx=xplct" string Causes records to be written only when explicitly specified by a call to fflush , close , or fclose . "deq = n" decimal Default extension quantity. "dna = filespec" string Default file-name string. "err" callback Error callback routine. "fop = val, val ,..." File-processing options: ctg
cbt
dfw
dlt
tef
cif
sup
scf
spl
tmd
tmp
nef
rck
wck
mxv
rwo
pos
rwc
sqoContiguous.
Contiguous-best-try.
Deferred write; only applicable to files opened for shared access.
Delete file on close.
Truncate at end-of-file.
Create if nonexistent.
Supersede.
Submit as command file on close.
Spool to system printer on close.
Temporary delete.
Temporary (no file directory).
Not end-of-file.
Read check compare operation.
Write check compare operation.
Maximize version number.
Rewind file on open.
Current position.
Rewind file on close.
File can only be processed in a sequential manner."fsz = n" decimal Fixed header size. "gbc = n" decimal The requested number of global buffers for a file. "mbc = n" decimal Multiblock count. "mbf = n" decimal Multibuffer count. "mrs = n" decimal Maximum record size. "pmt=usr-prmpt" string Prompts for terminal input. Any RMS input from a terminal device will be preceded by "usr-prmpt" when this option and "rop=pmt" are specified. "rat = val, val..." Record attributes: cr
blk
ftn
none
prnCarriage-return control.
Disallow records to span block boundaries.
FORTRAN print control.
Explicitly forces no carriage control.
Print file format."rfm = val" Record format: fix
stm
stmlf
stmcr
var
vfc
udfFixed-length record format.
RMS stream record format.
Stream format with line-feed terminator.
Stream format with carriage-return terminator.
Variable-length record format.
Variable-length record with fixed control.
Undefined."rop = val, val..." Record-processing operations: asy Asynchronous I/O. cco Cancel Ctrl/O (used with Terminal I/O). cvt Capitalizes characters on a read from the terminal. eof Positions the record stream to the end-of-file for the connect operation only. nlk Do not lock record. pmt Enables use of the prompt specified by "pmt=usr-prmpt" on input from the terminal. pta Eliminates any information in the type-ahead buffer on a read from the terminal. rea Locks record for a read operation for this process, while allowing other accessors to read the record. rlk Locks record for write. rne Suppresses echoing of input data on the screen as it is entered on the keyboard. rnf Indicates that Ctrl/U, Ctrl/R, and DELETE are not to be considered control commands on terminal input, but are to be passed to the application program. rrl Reads regardless of lock. syncsts Returns success status of RMS$_SYNCH if the requested service completes its task immediately. tmo Timeout I/O. tpt Allows put/write services using sequential record access mode to occur at any point in the file, truncating the file at that point. ulk Prohibits RMS from automatically unlocking records. wat Wait until record is available, if currently locked by another stream. rah Read ahead. wbh Write behind. "rtv=n" decimal The number of retrieval pointers that RMS has to maintain in memory (0 to 127,255). "shr = val" File sharing options: del
get
mse
nil
put
upd
upiAllows users to delete.
Allows users to read.
Allows mainstream access.
Prohibits file sharing.
Allows users to write.
Allows users to update.
Allows one or more writers."tmo = n" decimal I/O timeout value. In addition to these options, any option that takes a key value (such as "fop" or "rat") can be negated by prefixing the value with "no". For example, specify "fop=notmp" to clear the "tmp" bit in the "fop" field.
Notes
- While these options provide much flexibility and functionality, many of them can also cause severe problems if not used correctly.
- You cannot share the default DEC C for OpenVMS stream file I/O. If you wish to share files, you must specify "ctx=rec" to force record access mode. You must also specify the appropriate "shr" options depending on the type of access you want.
For more information on these options, see the OpenVMS Record Management Services Reference Manual manual.
The DEC C RTL opens the new file for reading and writing, and returns the corresponding file descriptor.If the file exists:
- A version number one greater than any existing version is assigned to the newly created file.
- By default, the new file inherits certain attributes from the existing version of the file unless those attributes are specified in the creat call. The following attributes are inherited:
- Record format (fab$b_rfm)
- Maximum record size (fab$w_mrs)
- Carriage control (fab$b_rat)
- File protection
If the file did not previously exist:
- It is given the file protection that results from performing a bitwise AND on the mode argument and the complement of the current protection mask.
- It defaults to stream format with line-feed record separator and implied carriage-return attributes.
See also open , close , read , write , and lseek in this section.
n A file descriptor. --1 Indicates errors, including protection violations, undefined directories, and conflicting file attributes.
In the UNIX system environment, the crmode and nocrmode functions set and unset the terminal from cbreak mode. In cbreak mode, a single input character can be processed without pressing Return. This mode of single-character input is only supported with the Curses input routine getch .
#include <curses.h>crmode()
nocrmode()
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