%ما هو (من)٪ 1 - تعريف
R Coronae Borealis variable
![Light curve of [[R Coronae Borealis]] from 1990 to 2017, showing the unprecedented deep minimum](https://commons.wikimedia.org/wiki/Special:FilePath/R Coronae Borealis light curve.png?width=200 "Light curve of [[R Coronae Borealis]] from 1990 to 2017, showing the unprecedented deep minimum")
CLASS OF VARIABLE STARS
R corona borealis star; R Corona Borealis Star; R Coronae Borealis variables; R Coronae Borealis star; R. Coronae Borealis star; R CrB star; RCrB; R Cor Bor star; RCB star
An R Coronae Borealis variable (abbreviated RCB, R CrB) is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation (a few tenths of a magnitude), and one irregular, unpredictably-sudden fading by 1 to 9 magnitudes. The prototype star R Coronae Borealis was discovered by the English amateur astronomer Edward Pigott in 1795, who first observed the enigmatic fadings of the star.
Variable (computer science)
STORAGE LOCATION PAIRED WITH A NAME, WHICH CONTAINS A VALUE
Program variable; Scalar variable; Variable scope; Simple variable; Variable (computing); Variable (programming); Variable lifetime; Scope and extent; Variable scope and extent; Variable extent; Variable (computer programming); Storage location; Assignable variable
In computer programming, a variable is an abstract storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value; or in simpler terms, a variable is a named container for a particular set of bits or type of data (like integer, float, string etc...).
environment variable
DYNAMIC VALUE THAT AFFECTS THE BEHAVIOR OF PROCESSES ON A COMPUTER
%SystemRoot%; %SystemDrive%; C：\WINDOWS; Environment variables; Env var; LC ALL; Environment (computing); Shell variable; Printenv; AppData; Environmental variable; %SYSTEMROOT%; $HOME; System variable; LD LIBRARY PATH; LIBPATH; LIBPATH (AIX); PROMPT (environment variable); Master environment; Pre-environment; Reserved environment variable; Master environment variable; Local environment variable; Local environment (computing); Local environment (DOS); Master environment (DOS); Pre-environment variable; Environment segment; Environment segment (computing); Environment segment (DOS); %APPEND%; %CONFIG%; %CMDLINE%; %COMSPEC%; %COPYCMD%; %DIRCMD%; %LANG%; %LANGSPEC%; %NO SEP%; %PATH%; %PROMPT%; %TEMP%; %TMP%; System environment; System environment (computing); System environment (DOS); System information variable; System information variable (computing); System information variable (DOS); $CLS (environment variable); Pseudo-environment variable; Unix environment variable; DOS environment variable; GEM environment variable; OS/2 environment variable; Windows environment variable; DOS pseudo-environment variable; Windows pseudo-environment variable; Dynamic environment variable; Dynamic environment variable (Microsoft); Dynamic environment variable (Windows); Dynamic environment variable (CMD); Dynamic environment variable (COMMAND.COM); Dynamic environment variable (DOS); System info variable; System information variable (COMMAND.COM); DOS system information variable; DOS system info variable; Internal variable (4DOS); Internal variable (4OS2); Internal variable (4NT); Internal variable (JP Software); 4DOS internal variable; 4OS2 internal variable; 4NT internal variable; 4DOS variable function; 4OS2 variable function; 4NT variable function; Variable function (4DOS); Variable function (4OS2); Variable function (4NT); Variable function (JP Software); JP Software variable function; JP Software internal variable; Dynamic environment variable (COMMAND); System information variable (COMMAND); DR-DOS system information variable; Novell DOS system information variable; Novell system information variable; OpenDOS system information variable; Caldera system information variable; RETURN (DOS command); %DRDOSCFG%; %NWDOSCFG%; %OPENDOSCFG%; %DRCOMSPEC%; %DRSYS%; %HOMEDIR%; %CMDCMDLINE%; %CMDEXTVERSION%; %RANDOM%; %TIME%; %SWITCHAR%; %PEXEC%; %OS%; %NOSOUND%; %NOCHAR%; %LOGINNAME%; %INFO%; %$DIR%; %$PAGE%; %$LENGTH%; %$WIDTH%; %VER%; %YESCHAR%; %$CLS%; %TASKMGRWINDIR%; %$SLICE%; %$ON%; %$OFF%; %$HEADER%; %$FOOTER%; %ERRORLEVEL%; %ERRORLVL%; %HOUR%; %HOUR24%; %MINUTE%; %MONTH%; %SECOND%; %YEAR%; %/%; %STATION%; %MDOS EXEC%; %AM PM%; %GREETING TIME%; %MONTH NAME%; %NDAY OF WEEK%; %OS VERSION%; %SHORT YEAR%; %LOGIN NAME%; %P STATION%; %FULL NAME%; % YEAR%; % CODEPAGE%; % COLUMNS%; % COUNTRY%; % DAY%; % HOUR%; % MINUTE%; % MONTH%; % ROWS%; % SECOND%; MS-DOS environment; FBP USER (environment variable); FBP USER; BEGINLIBPATH (environment variable); BEGINLIBPATH; ENDLIBPATH (environment variable); ENDLIBPATH; Unset (Unix); C\WINDOWS; System variables; CD (pseudo-environment variable); %DIRSIZE%; %NEWFILE%; %COMM%; %HTTP DIR%; %HOSTNAME%; %FTPDIR%; %TZ%; %SOCKETS%; %LIBPATH%; LIBPATH (environment variable); Windir (Windows environment variable); Windir (environment variable); LOCALAPPDATA (Windows environment variable); LOCALAPPDATA (environment variable); LOCALAPPDATA; ProgramFiles (Windows environment variable); ProgramFiles (environment variable); ProgramFiles; ProgramFiles(x86) (Windows environment variable); ProgramFiles(x86) (environment variable); ProgramFiles(x86); ProgramW6432; ProgramW6432 (environment variable); ProgramW6432 (Windows environment variable); CommonProgramFiles; CommonProgramFiles (Windows environment variable); CommonProgramFiles (environment variable); SystemDrive (Windows environment variable); SystemDrive (environment variable); SystemDrive; SystemRoot; SystemRoot (environment variable); SystemRoot (Windows environment variable); ALLUSERSPROFILE (environment variable); ALLUSERSPROFILE; ALLUSERSPROFILE (Windows environment variable); PROGRAMDATA (environment variable); PROGRAMDATA; PROGRAMDATA (Windows environment variable); USERDOMAIN (environment variable); USERDOMAIN; USERDOMAIN (Windows environment variable); USERPROFILE (environment variable); USERPROFILE; USERPROFILE (Windows environment variable); APPDATA (environment variable); APPDATA; APPDATA (Windows environment variable); %APPDATA%; %LOCALAPPDATA%; %ProgramFiles%; %ProgramFiles(x86)%; %ProgramW6432%; %CommonProgramFiles%; %ALLUSERSPROFILE%; %PROGRAMDATA%; %USERDOMAIN%; %USERPROFILE%; %windir%; CMDLINE (environment variable); CONFIG (environment variable); $LD LIBRARY PATH; %HOMEDRIVE%; %HOMEPATH%; Setenv; Unsetenv; Environment string
<programming, operating system> A variable that is bound in
the current environment. When evaluating an expression in
some environment, the evaluation of a variable consists of
looking up its name in the environment and substituting its
value.
Most programming languages have some concept of an environment
but in Unix shell scripts it has a specific meaning
slightly different from other contexts. In shell scripts,
environment variables are one kind of shell variable. They
differ from local variables and command line arguments in
that they are inheritted by a child process. Examples are
the PATH variable that tells the shell the file system
paths to search to find command executables and the TZ
variable which contains the local time zone. The variable
called "SHELL" specifies the type of shell being used.
These variables are used by commands or shell scripts to
discover things about the environment they are operating in.
Environment variables can be changed or created by the user
or a program.
To see a list of environment variables type "setenv" at the
csh or tcsh prompt or "set" at the sh, bash, jsh
or ksh prompt.
In other programming languages, e.g. functional programming
languages, the environment is extended with new bindings when
a function's parameters are bound to its {actual
arguments} or when new variables are declared. In a
block-structured procedural language, the environment
usually consists of a linked list of activation records.
(1999-01-26)
