زبان برنامه نویسی روبی | متغیرهای محیطی

سیده آمین ارمان

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عضویت
2016/05/10
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البرز
متغیر های از پیش تعریف شده زبان برنامه نویسی Ruby رفتار کل برنامه را تحت تاثیر قرار می دهند، بنابراین استفاده از آن ها در کتابخانه ها توصیه نمی شود.

جدول زیر، تمام متغیرهای از پیش تعریف شده زبان برنامه نویسی روبی را بصورت فهرست وار نشان می دهد.



Variable Name Description
$! The last exception object raised. The exception object can also be accessed using => in rescue clause.
$@ The stack backtrace for the last exception raised. The stack backtrace information can retrieved by Exception#backtrace method of the last exception.
$/ The input record separator (newline by default). gets, readline, etc., take their input record separator as optional argument.
$\ The output record separator (nil by default).
$, The output separator between the arguments to print and Array#join (nil by default). You can specify separator explicitly to Array#join.
$; The default separator for split (nil by default). You can specify separator explicitly for String#split.
$. The number of the last line read from the current input file. Equivalent to ARGF.lineno.
$< Synonym for ARGF.
$> Synonym for $defout.
$0 The name of the current Ruby program being executed.
$$ The process pid of the current Ruby program being executed.
$? The exit status of the last process terminated.
$: Synonym for $LOAD_PATH.
$DEBUG True if the -d or --debug command-line option is specified.
$defout The destination output for print and printf ($stdout by default).
$F The variable that receives the output from split when -a is specified. This variable is set if the -a command-line option is specified along with the -p or -n option.
$FILENAME The name of the file currently being read from ARGF. Equivalent to ARGF.filename.
$LOAD_PATH An array holding the directories to be searched when loading files with the load and require methods.
$SAFE The security level
0 --> No checks are performed on externally supplied (tainted) data. (default)
1 --> Potentially dangerous operations using tainted data are forbidden.
2 --> Potentially dangerous operations on processes and files are forbidden.
3 --> All newly created objects are considered tainted.
4 --> Modification of global data is forbidden.
$stdin Standard input (STDIN by default).
$stdout Standard output (STDOUT by default).
$stderr Standard error (STDERR by default).
$VERBOSE True if the -v, -w, or --verbose command-line option is specified.
$- x The value of interpreter option -x (x=0, a, d, F, i, K, l, p, v). These options are listed below
$-0 The value of interpreter option -x and alias of $/.
$-a The value of interpreter option -x and true if option -a is set. Read-only.
$-d The value of interpreter option -x and alias of $DEBUG
$-F The value of interpreter option -x and alias of $;.
$-i The value of interpreter option -x and in in-place-edit mode, holds the extension, otherwise nil. Can enable or disable in-place-edit mode.
$-I The value of interpreter option -x and alias of $:.
$-l The value of interpreter option -x and true if option -lis set. Read-only.
$-p The value of interpreter option -x and true if option -pis set. Read-only.
$_ The local variable, last string read by gets or readline in the current scope.
$~ The local variable, MatchData relating to the last match. Regex#match method returns the last match information.
$ n ($1, $2, $3...) The string matched in the nth group of the last pattern match. Equivalent to m[n], where m is a MatchData object.
$& The string matched in the last pattern match. Equivalent to m[0], where m is a MatchData object.
$` The string preceding the match in the last pattern match. Equivalent to m.pre_match, where m is a MatchData object.
$' The string following the match in the last pattern match. Equivalent to m.post_match, where m is a MatchData object.
$+ The string corresponding to the last successfully matched group in the last pattern match.
$+ The string corresponding to the last successfully matched group in the last pattern match.
 

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