The string representation of false
is “false”.
Returns the unique identifier for this proc, along with an indication of where the proc was defined.
Returns a human-readable description of the underlying method.
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" (1..3).method(:map).inspect #=> "#<Method: Range(Enumerable)#map()>"
In the latter case, the method description includes the “owner” of the original method (Enumerable
module, which is included into Range
).
inspect
also provides, when possible, method argument names (call sequence) and source location.
require 'net/http' Net::HTTP.method(:get).inspect #=> "#<Method: Net::HTTP.get(uri_or_host, path=..., port=...) <skip>/lib/ruby/2.7.0/net/http.rb:457>"
...
in argument definition means argument is optional (has some default value).
For methods defined in C (language core and extensions), location and argument names can’t be extracted, and only generic information is provided in form of *
(any number of arguments) or _
(some positional argument).
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" "cat".method(:+).inspect #=> "#<Method: String#+(_)>""
Dissociates meth from its current receiver. The resulting UnboundMethod
can subsequently be bound to a new object of the same class (see UnboundMethod
).
Returns a human-readable description of the underlying method.
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" (1..3).method(:map).inspect #=> "#<Method: Range(Enumerable)#map()>"
In the latter case, the method description includes the “owner” of the original method (Enumerable
module, which is included into Range
).
inspect
also provides, when possible, method argument names (call sequence) and source location.
require 'net/http' Net::HTTP.method(:get).inspect #=> "#<Method: Net::HTTP.get(uri_or_host, path=..., port=...) <skip>/lib/ruby/2.7.0/net/http.rb:457>"
...
in argument definition means argument is optional (has some default value).
For methods defined in C (language core and extensions), location and argument names can’t be extracted, and only generic information is provided in form of *
(any number of arguments) or _
(some positional argument).
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" "cat".method(:+).inspect #=> "#<Method: String#+(_)>""
Bind umeth to obj. If Klass was the class from which umeth was obtained, obj.kind_of?(Klass)
must be true.
class A def test puts "In test, class = #{self.class}" end end class B < A end class C < B end um = B.instance_method(:test) bm = um.bind(C.new) bm.call bm = um.bind(B.new) bm.call bm = um.bind(A.new) bm.call
produces:
In test, class = C In test, class = B prog.rb:16:in `bind': bind argument must be an instance of B (TypeError) from prog.rb:16
The calling thread will suspend execution and run this thr
.
Does not return until thr
exits or until the given limit
seconds have passed.
If the time limit expires, nil
will be returned, otherwise thr
is returned.
Any threads not joined will be killed when the main program exits.
If thr
had previously raised an exception and the ::abort_on_exception
or $DEBUG flags are not set, (so the exception has not yet been processed), it will be processed at this time.
a = Thread.new { print "a"; sleep(10); print "b"; print "c" } x = Thread.new { print "x"; Thread.pass; print "y"; print "z" } x.join # Let thread x finish, thread a will be killed on exit. #=> "axyz"
The following example illustrates the limit
parameter.
y = Thread.new { 4.times { sleep 0.1; puts 'tick... ' }} puts "Waiting" until y.join(0.15)
This will produce:
tick... Waiting tick... Waiting tick... tick...
Dump the name, id, and status of thr to a string.
Return a string containing a human-readable TracePoint
status.
Line number of the event
Create a new BigDecimal
object.
The initial value, as an Integer
, a Float
, a Rational
, a BigDecimal
, or a String
.
If it is a String
, spaces are ignored and unrecognized characters terminate the value.
The number of significant digits, as an Integer
. If omitted or 0, the number of significant digits is determined from the initial value.
The actual number of significant digits used in computation is usually larger than the specified number.
Whether an exception should be raised on invalid arguments. true
by default, if passed false
, just returns nil
for invalid.
TypeError
If the initial
type is neither Integer
, Float
, Rational
, nor BigDecimal
, this exception is raised.
TypeError
If the digits
is not an Integer
, this exception is raised.
ArgumentError
If initial
is a Float
, and the digits
is larger than Float::DIG + 1, this exception is raised.
ArgumentError
If the initial
is a Float
or Rational
, and the digits
value is omitted, this exception is raised.
Equivalent to:
io.write(sprintf(string, obj, ...))
or
$stdout.write(sprintf(string, obj, ...))
Prints each object in turn to $stdout
. If the output field separator ($,
) is not nil
, its contents will appear between each field. If the output record separator ($\
) is not nil
, it will be appended to the output. If no arguments are given, prints $_
. Objects that aren’t strings will be converted by calling their to_s
method.
print "cat", [1,2,3], 99, "\n" $, = ", " $\ = "\n" print "cat", [1,2,3], 99
produces:
cat12399 cat, 1, 2, 3, 99
Equivalent to Kernel::gets, except readline
raises EOFError
at end of file.
Returns an array containing the lines returned by calling Kernel.gets(sep)
until the end of file.
Returns the string resulting from applying format_string to any additional arguments. Within the format string, any characters other than format sequences are copied to the result.
The syntax of a format sequence is as follows.
%[flags][width][.precision]type
A format sequence consists of a percent sign, followed by optional flags, width, and precision indicators, then terminated with a field type character. The field type controls how the corresponding sprintf
argument is to be interpreted, while the flags modify that interpretation.
The field type characters are:
Field | Integer Format ------+-------------------------------------------------------------- b | Convert argument as a binary number. | Negative numbers will be displayed as a two's complement | prefixed with `..1'. B | Equivalent to `b', but uses an uppercase 0B for prefix | in the alternative format by #. d | Convert argument as a decimal number. i | Identical to `d'. o | Convert argument as an octal number. | Negative numbers will be displayed as a two's complement | prefixed with `..7'. u | Identical to `d'. x | Convert argument as a hexadecimal number. | Negative numbers will be displayed as a two's complement | prefixed with `..f' (representing an infinite string of | leading 'ff's). X | Equivalent to `x', but uses uppercase letters. Field | Float Format ------+-------------------------------------------------------------- e | Convert floating point argument into exponential notation | with one digit before the decimal point as [-]d.dddddde[+-]dd. | The precision specifies the number of digits after the decimal | point (defaulting to six). E | Equivalent to `e', but uses an uppercase E to indicate | the exponent. f | Convert floating point argument as [-]ddd.dddddd, | where the precision specifies the number of digits after | the decimal point. g | Convert a floating point number using exponential form | if the exponent is less than -4 or greater than or | equal to the precision, or in dd.dddd form otherwise. | The precision specifies the number of significant digits. G | Equivalent to `g', but use an uppercase `E' in exponent form. a | Convert floating point argument as [-]0xh.hhhhp[+-]dd, | which is consisted from optional sign, "0x", fraction part | as hexadecimal, "p", and exponential part as decimal. A | Equivalent to `a', but use uppercase `X' and `P'. Field | Other Format ------+-------------------------------------------------------------- c | Argument is the numeric code for a single character or | a single character string itself. p | The valuing of argument.inspect. s | Argument is a string to be substituted. If the format | sequence contains a precision, at most that many characters | will be copied. % | A percent sign itself will be displayed. No argument taken.
The flags modifies the behavior of the formats. The flag characters are:
Flag | Applies to | Meaning ---------+---------------+----------------------------------------- space | bBdiouxX | Leave a space at the start of | aAeEfgG | non-negative numbers. | (numeric fmt) | For `o', `x', `X', `b' and `B', use | | a minus sign with absolute value for | | negative values. ---------+---------------+----------------------------------------- (digit)$ | all | Specifies the absolute argument number | | for this field. Absolute and relative | | argument numbers cannot be mixed in a | | sprintf string. ---------+---------------+----------------------------------------- # | bBoxX | Use an alternative format. | aAeEfgG | For the conversions `o', increase the precision | | until the first digit will be `0' if | | it is not formatted as complements. | | For the conversions `x', `X', `b' and `B' | | on non-zero, prefix the result with ``0x'', | | ``0X'', ``0b'' and ``0B'', respectively. | | For `a', `A', `e', `E', `f', `g', and 'G', | | force a decimal point to be added, | | even if no digits follow. | | For `g' and 'G', do not remove trailing zeros. ---------+---------------+----------------------------------------- + | bBdiouxX | Add a leading plus sign to non-negative | aAeEfgG | numbers. | (numeric fmt) | For `o', `x', `X', `b' and `B', use | | a minus sign with absolute value for | | negative values. ---------+---------------+----------------------------------------- - | all | Left-justify the result of this conversion. ---------+---------------+----------------------------------------- 0 (zero) | bBdiouxX | Pad with zeros, not spaces. | aAeEfgG | For `o', `x', `X', `b' and `B', radix-1 | (numeric fmt) | is used for negative numbers formatted as | | complements. ---------+---------------+----------------------------------------- * | all | Use the next argument as the field width. | | If negative, left-justify the result. If the | | asterisk is followed by a number and a dollar | | sign, use the indicated argument as the width.
Examples of flags:
# `+' and space flag specifies the sign of non-negative numbers. sprintf("%d", 123) #=> "123" sprintf("%+d", 123) #=> "+123" sprintf("% d", 123) #=> " 123" # `#' flag for `o' increases number of digits to show `0'. # `+' and space flag changes format of negative numbers. sprintf("%o", 123) #=> "173" sprintf("%#o", 123) #=> "0173" sprintf("%+o", -123) #=> "-173" sprintf("%o", -123) #=> "..7605" sprintf("%#o", -123) #=> "..7605" # `#' flag for `x' add a prefix `0x' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%x", 123) #=> "7b" sprintf("%#x", 123) #=> "0x7b" sprintf("%+x", -123) #=> "-7b" sprintf("%x", -123) #=> "..f85" sprintf("%#x", -123) #=> "0x..f85" sprintf("%#x", 0) #=> "0" # `#' for `X' uses the prefix `0X'. sprintf("%X", 123) #=> "7B" sprintf("%#X", 123) #=> "0X7B" # `#' flag for `b' add a prefix `0b' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%b", 123) #=> "1111011" sprintf("%#b", 123) #=> "0b1111011" sprintf("%+b", -123) #=> "-1111011" sprintf("%b", -123) #=> "..10000101" sprintf("%#b", -123) #=> "0b..10000101" sprintf("%#b", 0) #=> "0" # `#' for `B' uses the prefix `0B'. sprintf("%B", 123) #=> "1111011" sprintf("%#B", 123) #=> "0B1111011" # `#' for `e' forces to show the decimal point. sprintf("%.0e", 1) #=> "1e+00" sprintf("%#.0e", 1) #=> "1.e+00" # `#' for `f' forces to show the decimal point. sprintf("%.0f", 1234) #=> "1234" sprintf("%#.0f", 1234) #=> "1234." # `#' for `g' forces to show the decimal point. # It also disables stripping lowest zeros. sprintf("%g", 123.4) #=> "123.4" sprintf("%#g", 123.4) #=> "123.400" sprintf("%g", 123456) #=> "123456" sprintf("%#g", 123456) #=> "123456."
The field width is an optional integer, followed optionally by a period and a precision. The width specifies the minimum number of characters that will be written to the result for this field.
Examples of width:
# padding is done by spaces, width=20 # 0 or radix-1. <------------------> sprintf("%20d", 123) #=> " 123" sprintf("%+20d", 123) #=> " +123" sprintf("%020d", 123) #=> "00000000000000000123" sprintf("%+020d", 123) #=> "+0000000000000000123" sprintf("% 020d", 123) #=> " 0000000000000000123" sprintf("%-20d", 123) #=> "123 " sprintf("%-+20d", 123) #=> "+123 " sprintf("%- 20d", 123) #=> " 123 " sprintf("%020x", -123) #=> "..ffffffffffffffff85"
For numeric fields, the precision controls the number of decimal places displayed. For string fields, the precision determines the maximum number of characters to be copied from the string. (Thus, the format sequence %10.10s
will always contribute exactly ten characters to the result.)
Examples of precisions:
# precision for `d', 'o', 'x' and 'b' is # minimum number of digits <------> sprintf("%20.8d", 123) #=> " 00000123" sprintf("%20.8o", 123) #=> " 00000173" sprintf("%20.8x", 123) #=> " 0000007b" sprintf("%20.8b", 123) #=> " 01111011" sprintf("%20.8d", -123) #=> " -00000123" sprintf("%20.8o", -123) #=> " ..777605" sprintf("%20.8x", -123) #=> " ..ffff85" sprintf("%20.8b", -11) #=> " ..110101" # "0x" and "0b" for `#x' and `#b' is not counted for # precision but "0" for `#o' is counted. <------> sprintf("%#20.8d", 123) #=> " 00000123" sprintf("%#20.8o", 123) #=> " 00000173" sprintf("%#20.8x", 123) #=> " 0x0000007b" sprintf("%#20.8b", 123) #=> " 0b01111011" sprintf("%#20.8d", -123) #=> " -00000123" sprintf("%#20.8o", -123) #=> " ..777605" sprintf("%#20.8x", -123) #=> " 0x..ffff85" sprintf("%#20.8b", -11) #=> " 0b..110101" # precision for `e' is number of # digits after the decimal point <------> sprintf("%20.8e", 1234.56789) #=> " 1.23456789e+03" # precision for `f' is number of # digits after the decimal point <------> sprintf("%20.8f", 1234.56789) #=> " 1234.56789000" # precision for `g' is number of # significant digits <-------> sprintf("%20.8g", 1234.56789) #=> " 1234.5679" # <-------> sprintf("%20.8g", 123456789) #=> " 1.2345679e+08" # precision for `s' is # maximum number of characters <------> sprintf("%20.8s", "string test") #=> " string t"
Examples:
sprintf("%d %04x", 123, 123) #=> "123 007b" sprintf("%08b '%4s'", 123, 123) #=> "01111011 ' 123'" sprintf("%1$*2$s %2$d %1$s", "hello", 8) #=> " hello 8 hello" sprintf("%1$*2$s %2$d", "hello", -8) #=> "hello -8" sprintf("%+g:% g:%-g", 1.23, 1.23, 1.23) #=> "+1.23: 1.23:1.23" sprintf("%u", -123) #=> "-123"
For more complex formatting, Ruby supports a reference by name. %<name>s style uses format style, but %{name} style doesn’t.
Examples:
sprintf("%<foo>d : %<bar>f", { :foo => 1, :bar => 2 }) #=> 1 : 2.000000 sprintf("%{foo}f", { :foo => 1 }) # => "1f"
Returns the string resulting from applying format_string to any additional arguments. Within the format string, any characters other than format sequences are copied to the result.
The syntax of a format sequence is as follows.
%[flags][width][.precision]type
A format sequence consists of a percent sign, followed by optional flags, width, and precision indicators, then terminated with a field type character. The field type controls how the corresponding sprintf
argument is to be interpreted, while the flags modify that interpretation.
The field type characters are:
Field | Integer Format ------+-------------------------------------------------------------- b | Convert argument as a binary number. | Negative numbers will be displayed as a two's complement | prefixed with `..1'. B | Equivalent to `b', but uses an uppercase 0B for prefix | in the alternative format by #. d | Convert argument as a decimal number. i | Identical to `d'. o | Convert argument as an octal number. | Negative numbers will be displayed as a two's complement | prefixed with `..7'. u | Identical to `d'. x | Convert argument as a hexadecimal number. | Negative numbers will be displayed as a two's complement | prefixed with `..f' (representing an infinite string of | leading 'ff's). X | Equivalent to `x', but uses uppercase letters. Field | Float Format ------+-------------------------------------------------------------- e | Convert floating point argument into exponential notation | with one digit before the decimal point as [-]d.dddddde[+-]dd. | The precision specifies the number of digits after the decimal | point (defaulting to six). E | Equivalent to `e', but uses an uppercase E to indicate | the exponent. f | Convert floating point argument as [-]ddd.dddddd, | where the precision specifies the number of digits after | the decimal point. g | Convert a floating point number using exponential form | if the exponent is less than -4 or greater than or | equal to the precision, or in dd.dddd form otherwise. | The precision specifies the number of significant digits. G | Equivalent to `g', but use an uppercase `E' in exponent form. a | Convert floating point argument as [-]0xh.hhhhp[+-]dd, | which is consisted from optional sign, "0x", fraction part | as hexadecimal, "p", and exponential part as decimal. A | Equivalent to `a', but use uppercase `X' and `P'. Field | Other Format ------+-------------------------------------------------------------- c | Argument is the numeric code for a single character or | a single character string itself. p | The valuing of argument.inspect. s | Argument is a string to be substituted. If the format | sequence contains a precision, at most that many characters | will be copied. % | A percent sign itself will be displayed. No argument taken.
The flags modifies the behavior of the formats. The flag characters are:
Flag | Applies to | Meaning ---------+---------------+----------------------------------------- space | bBdiouxX | Leave a space at the start of | aAeEfgG | non-negative numbers. | (numeric fmt) | For `o', `x', `X', `b' and `B', use | | a minus sign with absolute value for | | negative values. ---------+---------------+----------------------------------------- (digit)$ | all | Specifies the absolute argument number | | for this field. Absolute and relative | | argument numbers cannot be mixed in a | | sprintf string. ---------+---------------+----------------------------------------- # | bBoxX | Use an alternative format. | aAeEfgG | For the conversions `o', increase the precision | | until the first digit will be `0' if | | it is not formatted as complements. | | For the conversions `x', `X', `b' and `B' | | on non-zero, prefix the result with ``0x'', | | ``0X'', ``0b'' and ``0B'', respectively. | | For `a', `A', `e', `E', `f', `g', and 'G', | | force a decimal point to be added, | | even if no digits follow. | | For `g' and 'G', do not remove trailing zeros. ---------+---------------+----------------------------------------- + | bBdiouxX | Add a leading plus sign to non-negative | aAeEfgG | numbers. | (numeric fmt) | For `o', `x', `X', `b' and `B', use | | a minus sign with absolute value for | | negative values. ---------+---------------+----------------------------------------- - | all | Left-justify the result of this conversion. ---------+---------------+----------------------------------------- 0 (zero) | bBdiouxX | Pad with zeros, not spaces. | aAeEfgG | For `o', `x', `X', `b' and `B', radix-1 | (numeric fmt) | is used for negative numbers formatted as | | complements. ---------+---------------+----------------------------------------- * | all | Use the next argument as the field width. | | If negative, left-justify the result. If the | | asterisk is followed by a number and a dollar | | sign, use the indicated argument as the width.
Examples of flags:
# `+' and space flag specifies the sign of non-negative numbers. sprintf("%d", 123) #=> "123" sprintf("%+d", 123) #=> "+123" sprintf("% d", 123) #=> " 123" # `#' flag for `o' increases number of digits to show `0'. # `+' and space flag changes format of negative numbers. sprintf("%o", 123) #=> "173" sprintf("%#o", 123) #=> "0173" sprintf("%+o", -123) #=> "-173" sprintf("%o", -123) #=> "..7605" sprintf("%#o", -123) #=> "..7605" # `#' flag for `x' add a prefix `0x' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%x", 123) #=> "7b" sprintf("%#x", 123) #=> "0x7b" sprintf("%+x", -123) #=> "-7b" sprintf("%x", -123) #=> "..f85" sprintf("%#x", -123) #=> "0x..f85" sprintf("%#x", 0) #=> "0" # `#' for `X' uses the prefix `0X'. sprintf("%X", 123) #=> "7B" sprintf("%#X", 123) #=> "0X7B" # `#' flag for `b' add a prefix `0b' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%b", 123) #=> "1111011" sprintf("%#b", 123) #=> "0b1111011" sprintf("%+b", -123) #=> "-1111011" sprintf("%b", -123) #=> "..10000101" sprintf("%#b", -123) #=> "0b..10000101" sprintf("%#b", 0) #=> "0" # `#' for `B' uses the prefix `0B'. sprintf("%B", 123) #=> "1111011" sprintf("%#B", 123) #=> "0B1111011" # `#' for `e' forces to show the decimal point. sprintf("%.0e", 1) #=> "1e+00" sprintf("%#.0e", 1) #=> "1.e+00" # `#' for `f' forces to show the decimal point. sprintf("%.0f", 1234) #=> "1234" sprintf("%#.0f", 1234) #=> "1234." # `#' for `g' forces to show the decimal point. # It also disables stripping lowest zeros. sprintf("%g", 123.4) #=> "123.4" sprintf("%#g", 123.4) #=> "123.400" sprintf("%g", 123456) #=> "123456" sprintf("%#g", 123456) #=> "123456."
The field width is an optional integer, followed optionally by a period and a precision. The width specifies the minimum number of characters that will be written to the result for this field.
Examples of width:
# padding is done by spaces, width=20 # 0 or radix-1. <------------------> sprintf("%20d", 123) #=> " 123" sprintf("%+20d", 123) #=> " +123" sprintf("%020d", 123) #=> "00000000000000000123" sprintf("%+020d", 123) #=> "+0000000000000000123" sprintf("% 020d", 123) #=> " 0000000000000000123" sprintf("%-20d", 123) #=> "123 " sprintf("%-+20d", 123) #=> "+123 " sprintf("%- 20d", 123) #=> " 123 " sprintf("%020x", -123) #=> "..ffffffffffffffff85"
For numeric fields, the precision controls the number of decimal places displayed. For string fields, the precision determines the maximum number of characters to be copied from the string. (Thus, the format sequence %10.10s
will always contribute exactly ten characters to the result.)
Examples of precisions:
# precision for `d', 'o', 'x' and 'b' is # minimum number of digits <------> sprintf("%20.8d", 123) #=> " 00000123" sprintf("%20.8o", 123) #=> " 00000173" sprintf("%20.8x", 123) #=> " 0000007b" sprintf("%20.8b", 123) #=> " 01111011" sprintf("%20.8d", -123) #=> " -00000123" sprintf("%20.8o", -123) #=> " ..777605" sprintf("%20.8x", -123) #=> " ..ffff85" sprintf("%20.8b", -11) #=> " ..110101" # "0x" and "0b" for `#x' and `#b' is not counted for # precision but "0" for `#o' is counted. <------> sprintf("%#20.8d", 123) #=> " 00000123" sprintf("%#20.8o", 123) #=> " 00000173" sprintf("%#20.8x", 123) #=> " 0x0000007b" sprintf("%#20.8b", 123) #=> " 0b01111011" sprintf("%#20.8d", -123) #=> " -00000123" sprintf("%#20.8o", -123) #=> " ..777605" sprintf("%#20.8x", -123) #=> " 0x..ffff85" sprintf("%#20.8b", -11) #=> " 0b..110101" # precision for `e' is number of # digits after the decimal point <------> sprintf("%20.8e", 1234.56789) #=> " 1.23456789e+03" # precision for `f' is number of # digits after the decimal point <------> sprintf("%20.8f", 1234.56789) #=> " 1234.56789000" # precision for `g' is number of # significant digits <-------> sprintf("%20.8g", 1234.56789) #=> " 1234.5679" # <-------> sprintf("%20.8g", 123456789) #=> " 1.2345679e+08" # precision for `s' is # maximum number of characters <------> sprintf("%20.8s", "string test") #=> " string t"
Examples:
sprintf("%d %04x", 123, 123) #=> "123 007b" sprintf("%08b '%4s'", 123, 123) #=> "01111011 ' 123'" sprintf("%1$*2$s %2$d %1$s", "hello", 8) #=> " hello 8 hello" sprintf("%1$*2$s %2$d", "hello", -8) #=> "hello -8" sprintf("%+g:% g:%-g", 1.23, 1.23, 1.23) #=> "+1.23: 1.23:1.23" sprintf("%u", -123) #=> "-123"
For more complex formatting, Ruby supports a reference by name. %<name>s style uses format style, but %{name} style doesn’t.
Examples:
sprintf("%<foo>d : %<bar>f", { :foo => 1, :bar => 2 }) #=> 1 : 2.000000 sprintf("%{foo}f", { :foo => 1 }) # => "1f"
Converts arg to an Integer
. Numeric
types are converted directly (with floating point numbers being truncated). base (0, or between 2 and 36) is a base for integer string representation. If arg is a String
, when base is omitted or equals zero, radix indicators (0
, 0b
, and 0x
) are honored. In any case, strings should be strictly conformed to numeric representation. This behavior is different from that of String#to_i
. Non string values will be converted by first trying to_int
, then to_i
.
Passing nil
raises a TypeError
, while passing a String
that does not conform with numeric representation raises an ArgumentError
. This behavior can be altered by passing exception: false
, in this case a not convertible value will return nil
.
Integer(123.999) #=> 123 Integer("0x1a") #=> 26 Integer(Time.new) #=> 1204973019 Integer("0930", 10) #=> 930 Integer("111", 2) #=> 7 Integer(nil) #=> TypeError: can't convert nil into Integer Integer("x") #=> ArgumentError: invalid value for Integer(): "x" Integer("x", exception: false) #=> nil
Returns arg as a String
.
First tries to call its to_str
method, then its to_s
method.
String(self) #=> "main" String(self.class) #=> "Object" String(123456) #=> "123456"
Passes each entry in enum to block. Returns the first for which block is not false. If no object matches, calls ifnone and returns its result when it is specified, or returns nil
otherwise.
If no block is given, an enumerator is returned instead.
(1..100).detect #=> #<Enumerator: 1..100:detect> (1..100).find #=> #<Enumerator: 1..100:find> (1..10).detect { |i| i % 5 == 0 && i % 7 == 0 } #=> nil (1..10).find { |i| i % 5 == 0 && i % 7 == 0 } #=> nil (1..10).detect(-> {0}) { |i| i % 5 == 0 && i % 7 == 0 } #=> 0 (1..10).find(-> {0}) { |i| i % 5 == 0 && i % 7 == 0 } #=> 0 (1..100).detect { |i| i % 5 == 0 && i % 7 == 0 } #=> 35 (1..100).find { |i| i % 5 == 0 && i % 7 == 0 } #=> 35
Returns a new array with the results of running block once for every element in enum.
If no block is given, an enumerator is returned instead.
(1..4).map { |i| i*i } #=> [1, 4, 9, 16] (1..4).collect { "cat" } #=> ["cat", "cat", "cat", "cat"]
Combines all elements of enum by applying a binary operation, specified by a block or a symbol that names a method or operator.
The inject and reduce methods are aliases. There is no performance benefit to either.
If you specify a block, then for each element in enum the block is passed an accumulator value (memo) and the element. If you specify a symbol instead, then each element in the collection will be passed to the named method of memo. In either case, the result becomes the new value for memo. At the end of the iteration, the final value of memo is the return value for the method.
If you do not explicitly specify an initial value for memo, then the first element of collection is used as the initial value of memo.
# Sum some numbers (5..10).reduce(:+) #=> 45 # Same using a block and inject (5..10).inject { |sum, n| sum + n } #=> 45 # Multiply some numbers (5..10).reduce(1, :*) #=> 151200 # Same using a block (5..10).inject(1) { |product, n| product * n } #=> 151200 # find the longest word longest = %w{ cat sheep bear }.inject do |memo, word| memo.length > word.length ? memo : word end longest #=> "sheep"
Returns true
if any member of enum equals obj. Equality is tested using ==
.
(1..10).include? 5 #=> true (1..10).include? 15 #=> false (1..10).member? 5 #=> true (1..10).member? 15 #=> false
Returns an enumerator object generated from this enumerator and given enumerables.
e = (1..3).chain([4, 5]) e.to_a #=> [1, 2, 3, 4, 5]
Computes the sine of decimal
to the specified number of digits of precision, numeric
.
If decimal
is Infinity or NaN, returns NaN.
BigMath.sin(BigMath.PI(5)/4, 5).to_s #=> "0.70710678118654752440082036563292800375e0"