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Move the cursor to coordinates (y,x), get a character from the terminal screen, and echo it on the specified window. The mvgetch function acts on the stdscr window.
#include <curses.h>int mvgetch (int y, int x);
int mvwgetch (WINDOW *win, int y, int x);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.
The mvgetch and mvwgetch functions refresh the specified window before fetching the character.
x The returned character. ERR Indicates that the function causes the screen to scroll illegally. For more information, see the scrollok function in this section.
Move the cursor to coordinates (y,x), get a string from the terminal screen, store it in the variable str which must be large enough to contain the string, and echo it on the specified window. The mvgetstr function acts on the stdscr window.
#include <curses.h>int mvgetstr (int y, int x, char *str);
int mvwgetstr (WINDOW *win, int y, int x, char *str);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.str
The string that is displayed.
The mvgetstr and mvwgetstr functions strip the new-line terminator (\n) from the string.
OK Indicates success. ERR Indicates that the function causes the screen to scroll illegally.
Move the cursor to coordinates (y,x) and return the character on the specified window without making changes to the window. The mvinch function acts on the stdscr window.
#include <curses.h>int mvinch (int y, int x);
int mvwinch (WINDOW *win, int y, int x);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.
x The returned character. ERR Indicates an input error.
Move the cursor to coordinates (y,x) and insert the character ch into the specified window. The mvinsch function acts on the stdscr window.
#include <curses.h>int mvinsch (int y, int x, char ch);
int mvwinsch (WINDOW *win, int y, int x, char ch);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.ch
The character to be inserted at the window's coordinates.
After the character is inserted, each character on the line shifts to the right, and the last character on the line is deleted.
OK Indicates success. ERR Indicates that the function makes the screen scroll illegally. For more information, see the scrollok function in this section.
Move the cursor to coordinates (y,x) and insert the specified string into the specified window. The mvinsstr function acts on the stdscr window.
#include <curses.h>int mvinsstr (int y, int x, char *str);
int mvwinsstr (WINDOW *win, int y, int x, char *str);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.str
The string that is displayed.
Each character after the string shifts to the right, and the last character disappears. The mvinsstr and mvwinsstr functions are specific to Compaq C for OpenVMS Systems and are not portable.
OK Indicates success. ERR Indicates that the function makes the screen scroll illegally. For more information, see the scrollok function in this section.
Moves the starting position of the window to the specified (y,x) coordinates.
#include <curses.h>mvwin (WINDOW *win, int y, int x);
win
A pointer to the window.y
A window coordinate.x
A window coordinate.
When moving subwindows, the mvwin function does not rewrite the contents of the subwindow on the underlying window at the new position. If you write anything to the subwindow after the move, the function also writes to the underlying window.
OK Indicates success. ERR Indicates that moving the window put part or all of the window off the edge of the terminal screen. The terminal screen remains unaltered.
Creates a new window with numlines lines and numcols columns starting at the coordinates (begin_y,begin_x) on the terminal screen.
#include <curses.h>WINDOW *newwin (int numlines, int numcols, int begin_y, int begin_x);
numlines
If it is 0, the newwin function sets that dimension to LINES (begin_y). To get a new window of dimensions LINES by COLS, use the following line:
newwin (0, 0, 0, 0)numcols
If it is 0, the newwin function sets that dimension to COLS (begin_x). Thus, to get a new window of dimensions LINES by COLS, use the following line:
newwin (0, 0, 0, 0)begin_y
A window coordinate.begin_x
A window coordinate.
x The address of the allocated window. ERR Indicates an error.
Increases or decreases process priority relative to the process current priority by the amount of the argument. This function is nonreentrant.
#include <unistd.h>int nice (int increment);
increment
As a positive argument, decreases priority; as a negative argument, increases priority. Issuing nice(0) restores the base priority. The resulting priority cannot be less than 1, or greater than the process's base priority. If it is, the nice function quietly does nothing.
When a process calls the vfork function, the resulting child inherits the parent's priority.See also vfork in this section.
0 Indicates success. --1 Indicates failure.
The nl and nonl functions are provided only for UNIX software compatibility and have no function in the OpenVMS environment.
#include <curses.h>void nl (void);
void nonl (void);
Returns a pointer to a string that contains information obtained from the program's current locale.
#include <langinfo.h>char *nl_langinfo (nl_item item);
item
The name of a constant that specifies the information required. These constants are defined in <langinfo.h> .The following constants are valid:
Constant Category Description D_T_FMT LC_TIME String for formatting date and time D_FMT LC_TIME String for formatting date T_FMT LC_TIME String for formatting time T_FMT_AMPM LC_TIME Time format with AM/PM string AM_STR LC_TIME String that represents AM in 12-hour clock notation PM_STR LC_TIME String that represents PM in 12-hour clock notation DAY_1 LC_TIME The name of the first day of the week ... DAY_7 LC_TIME The name of the seventh day of the week ABDAY_1 LC_TIME The abbreviated name of the first day of the week ... ABDAY_7 LC_TIME The abbreviated name of the seventh day of the week MON_1 LC_TIME The name of the first month in the year ... MON_12 LC_TIME The name of the twelfth month in the year ABMON_1 LC_TIME The abbreviated name of the first month in the year ... ABMON_12 LC_TIME The abbreviated name of the twelfth month in the year ERA LC_TIME Era description strings ERA_D_FMT LC_TIME Era date format string ERA_T_FMT LC_TIME Era time format ERA_D_T_FMT LC_TIME Era date and time format ALT_DIGITS LC_TIME Alternative symbols for digits RADIXCHAR LC_NUMERIC The radix character THOUSEP LC_NUMERIC The character used to separate groups of digits in non-monetary values YESEXP LC_MESSAGES The expression for affirmative responses to yes/no questions NOEXP LC_MESSAGES The expression for negative responses to yes/no questions CRNCYSTR LC_MONETARY The currency symbol. It is preceded by one of the following:
- A minus (-) if the symbol is to appear before the value
- A plus (+) if the symbol is to appear after the value
- A period (.) if the symbol replaces the radix character
CODESET LC_CTYPE Codeset name
If the current locale does not have language information defined, the function returns information from the C locale. The program should not modify the string returned by the function. This string might be overwritten by subsequent calls to nl_langinfo .If the setlocale function is called after a call to nl_langinfo , then the pointer returned by the previous call to nl_langinfo will be unspecified. In this case, the nl_langinfo function should be called again.
x Pointer to the string containing the requested information. If item is invalid, the function returns an empty string.
#include <stdio.h> #include <locale.h> #include <langinfo.h> /* This test sets up the British English locale, and then inquires on the */ /* data and time format, first day of the week, and abbreviated first */ /* day of the week. */ #include <stdlib.h> #include <string.h> int main() { char *return_val; char *nl_ptr; /* set the locale, with user supplied locale name */ return_val = setlocale(LC_ALL, "en_gb.iso8859-1"); if (return_val == NULL) { printf("ERROR : The locale is unknown"); exit(1); } printf("+-----------------------------------------------------+\n"); /* Get the date and time format from the locale. */ printf("D_T_FMT = "); /* Compare the returned string from nl_langinfo with an empty */ /* string. */ if (!strcmp((nl_ptr = (char *) nl_langinfo(D_T_FMT)), "")) { /* The string returned was empty this could mean that either */ /* 1) The locale does not contain a value for this item */ /* 2) The value for this item is an empty string */ printf("nl_langinfo returned an empty string\n"); } else { /* Display the date and time format */ printf("%s\n", nl_ptr); } /* Get the full name for the first day of the week from locale */ printf("DAY_1 = "); /* Compare the returned string from nl_langinfo with an empty */ /* string. */ if (!strcmp((nl_ptr = (char *) nl_langinfo(DAY_1)), "")) { /* The string returned was empty this could mean that either */ /* 1) The locale does not contain a value for the first day of */ /* the week */ /* 2) The value for the first day of the week is an empty string */ printf("nl_langinfo returned an empty string\n"); } else { /* Display the full name of the first day of the week */ printf("%s\n", nl_ptr); } /* Get the abbreviated name for the first day of the week from locale */ printf("ABDAY_1 = "); /* Compare the returned string from nl_langinfo with an empty */ /* string. */ if (!strcmp((nl_ptr = (char *) nl_langinfo(ABDAY_1)), "")) { /* The string returned was empty this could mean that either */ /* 1) The locale does not contain a value for the first day of */ /* the week */ /* 2) The value for the first day of the week is an empty string */ printf("nl_langinfo returned an empty string\n"); } else { /* Display the abbreviated name of the first day of the week */ printf("%s\n", nl_ptr); } }Running the example program produces the following result:
+-----------------------------------------------------+ D_T_FMT = %a %e %b %H:%M:%S %Y DAY_1 = Sunday ABDAY_1 = Sun
Generates uniformly distributed pseudorandom number sequences. Returns 48-bit signed long integers.
#include <stdlib.h>long int nrand48 (unsigned short int xsubi[3]);
xsubi
An array of three short int that, when concatentated together, form a 48-bit integer.
This function generates pseudorandom numbers using the linear congruential algorithm and 48-bit integer arithmetic.The nrand48 function returns nonnegative, long integers uniformly distributed over the range of y values, such that 0 <= y < 231 .
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 nrand48 function requires that the calling program pass an array as the xsubi argument, which for the first call must be initialized to the initial value of the pseudorandom number sequence. Unlike the drand48 function, it is not necessary to call an initialization function prior to the first call.
By using different arguments, the nrand48 function allows separate modules of a large program to generate several independent sequences of pseudorandom numbers. For example, the sequence of numbers that one module generates does not depend upon how many times the functions are called by other modules.
n Returns nonnegative, long integers over the range 0 <= y < 2 31 .
Opens a file for reading, writing, or editing. It positions the file at its beginning (byte 0).
#include <fcntl.h>int open (const char *file_spec, int flags, mode_t mode); (ANSI C)
int open (const char *file_spec, int flags, ...); (DEC C EXTENSION)
file_spec
A null-terminated character string containing a valid file specification. If you specify a directory in the file_spec and it is a search list that contains an error, Compaq C interprets it as a file open error.flags
The following values are defined in the <file.h> header file:
O_RDONLY Open for reading only O_WRONLY Open for writing only O_RDWR Open for reading and writing O_NDELAY Open for asynchronous input O_APPEND Append on each write O_CREAT Create a file if it does not exist O_TRUNC Create a new version of this file O_EXCL Error if attempting to create existing file These flags are set using the bitwise OR operator (|) to separate specified flags.
Opening a file with O_APPEND causes each write on the file to be appended to the end. (In contrast, with the VAX C RTL the behavior of files opened in append mode was to start at EOF and, thereafter, write at the current file position.)
If O_TRUNC is specified and the file exists, open creates a new file by incrementing the version number by 1, leaving the old version in existence.
If O_CREAT is set and the named file does not exist, the Compaq C RTL creates it with any attributes specified in the fourth and subsequent arguments (...). If O_EXCL is set with O_CREAT and the named file exists, the attempted open returns an error.
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 separate specified modes. The modes are:
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 access privileges as the owner. A WRITE privilege also implies a DELETE privilege.
...
Optional file attribute arguments. The file attribute arguments are the same as those used in the creat function. For more information, see the creat function.
If a version of the file exists, a new file created with open inherits certain attributes from the existing file unless those attributes are specified in the open call. The following attributes are inherited: record format, maximum record size, carriage control, and file protection.
Notes
- If you intend to do random writing to a file, the file must be opened for update by specifying a flags value of O_RDWR.
- To create files with OpenVMS RMS default protections by 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.
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