Invokes the given block passing in successive elements from self, deleting elements for which the block returns a false value.
The array may not be changed instantly every time the block is called.
If changes were made, it will return self, otherwise it returns nil.
If no block is given, an Enumerator is returned instead.
See also Array#keep_if.
Array#filter! is an alias for Array#select!.
Returns a new array containing all elements of ary for which the given block returns a true value.
If no block is given, an Enumerator is returned instead.
[1,2,3,4,5].select {|num| num.even? } #=> [2, 4] a = %w[ a b c d e f ] a.select {|v| v =~ /[aeiou]/ } #=> ["a", "e"]
See also Enumerable#select.
Array#filter is an alias for Array#select.
Invokes the given block passing in successive elements from self, deleting elements for which the block returns a false value.
The array may not be changed instantly every time the block is called.
If changes were made, it will return self, otherwise it returns nil.
If no block is given, an Enumerator is returned instead.
See also Array#keep_if.
Array#filter! is an alias for Array#select!.
Assumes that self is an array of arrays and transposes the rows and columns.
a = [[1,2], [3,4], [5,6]] a.transpose #=> [[1, 3, 5], [2, 4, 6]]
If the length of the subarrays don’t match, an IndexError is raised.
Returns a copy of self with all nil elements removed.
[ "a", nil, "b", nil, "c", nil ].compact #=> [ "a", "b", "c" ]
Removes nil elements from the array.
Returns nil if no changes were made, otherwise returns the array.
[ "a", nil, "b", nil, "c" ].compact! #=> [ "a", "b", "c" ] [ "a", "b", "c" ].compact! #=> nil
Drops first n elements from ary and returns the rest of the elements in an array.
If a negative number is given, raises an ArgumentError.
See also Array#take
a = [1, 2, 3, 4, 5, 0] a.drop(3) #=> [4, 5, 0]
See also Enumerable#none?
See also Enumerable#one?
provides a unified clone operation, for REXML::XPathParser to use across multiple Object+ types
Packs the contents of arr into a binary sequence according to the directives in aTemplateString (see the table below) Directives “A,” “a,” and “Z” may be followed by a count, which gives the width of the resulting field. The remaining directives also may take a count, indicating the number of array elements to convert. If the count is an asterisk (“*”), all remaining array elements will be converted. Any of the directives “sSiIlL” may be followed by an underscore (“_”) or exclamation mark (“!”) to use the underlying platform’s native size for the specified type; otherwise, they use a platform-independent size. Spaces are ignored in the template string. See also String#unpack.
a = [ "a", "b", "c" ] n = [ 65, 66, 67 ] a.pack("A3A3A3") #=> "a b c " a.pack("a3a3a3") #=> "a\000\000b\000\000c\000\000" n.pack("ccc") #=> "ABC"
If aBufferString is specified and its capacity is enough, pack uses it as the buffer and returns it. When the offset is specified by the beginning of aTemplateString, the result is filled after the offset. If original contents of aBufferString exists and it’s longer than the offset, the rest of offsetOfBuffer are overwritten by the result. If it’s shorter, the gap is filled with “\0”.
Note that “buffer:” option does not guarantee not to allocate memory in pack. If the capacity of aBufferString is not enough, pack allocates memory.
Directives for pack.
Integer | Array |
Directive | Element | Meaning
----------------------------------------------------------------------------
C | Integer | 8-bit unsigned (unsigned char)
S | Integer | 16-bit unsigned, native endian (uint16_t)
L | Integer | 32-bit unsigned, native endian (uint32_t)
Q | Integer | 64-bit unsigned, native endian (uint64_t)
J | Integer | pointer width unsigned, native endian (uintptr_t)
| | (J is available since Ruby 2.3.)
| |
c | Integer | 8-bit signed (signed char)
s | Integer | 16-bit signed, native endian (int16_t)
l | Integer | 32-bit signed, native endian (int32_t)
q | Integer | 64-bit signed, native endian (int64_t)
j | Integer | pointer width signed, native endian (intptr_t)
| | (j is available since Ruby 2.3.)
| |
S_ S! | Integer | unsigned short, native endian
I I_ I! | Integer | unsigned int, native endian
L_ L! | Integer | unsigned long, native endian
Q_ Q! | Integer | unsigned long long, native endian (ArgumentError
| | if the platform has no long long type.)
| | (Q_ and Q! is available since Ruby 2.1.)
J! | Integer | uintptr_t, native endian (same with J)
| | (J! is available since Ruby 2.3.)
| |
s_ s! | Integer | signed short, native endian
i i_ i! | Integer | signed int, native endian
l_ l! | Integer | signed long, native endian
q_ q! | Integer | signed long long, native endian (ArgumentError
| | if the platform has no long long type.)
| | (q_ and q! is available since Ruby 2.1.)
j! | Integer | intptr_t, native endian (same with j)
| | (j! is available since Ruby 2.3.)
| |
S> s> S!> s!> | Integer | same as the directives without ">" except
L> l> L!> l!> | | big endian
I!> i!> | | (available since Ruby 1.9.3)
Q> q> Q!> q!> | | "S>" is same as "n"
J> j> J!> j!> | | "L>" is same as "N"
| |
S< s< S!< s!< | Integer | same as the directives without "<" except
L< l< L!< l!< | | little endian
I!< i!< | | (available since Ruby 1.9.3)
Q< q< Q!< q!< | | "S<" is same as "v"
J< j< J!< j!< | | "L<" is same as "V"
| |
n | Integer | 16-bit unsigned, network (big-endian) byte order
N | Integer | 32-bit unsigned, network (big-endian) byte order
v | Integer | 16-bit unsigned, VAX (little-endian) byte order
V | Integer | 32-bit unsigned, VAX (little-endian) byte order
| |
U | Integer | UTF-8 character
w | Integer | BER-compressed integer
Float | Array |
Directive | Element | Meaning
---------------------------------------------------------------------------
D d | Float | double-precision, native format
F f | Float | single-precision, native format
E | Float | double-precision, little-endian byte order
e | Float | single-precision, little-endian byte order
G | Float | double-precision, network (big-endian) byte order
g | Float | single-precision, network (big-endian) byte order
String | Array |
Directive | Element | Meaning
---------------------------------------------------------------------------
A | String | arbitrary binary string (space padded, count is width)
a | String | arbitrary binary string (null padded, count is width)
Z | String | same as ``a'', except that null is added with *
B | String | bit string (MSB first)
b | String | bit string (LSB first)
H | String | hex string (high nibble first)
h | String | hex string (low nibble first)
u | String | UU-encoded string
M | String | quoted printable, MIME encoding (see also RFC2045)
| | (text mode but input must use LF and output LF)
m | String | base64 encoded string (see RFC 2045)
| | (if count is 0, no line feed are added, see RFC 4648)
| | (count specifies input bytes between each LF,
| | rounded down to nearest multiple of 3)
P | String | pointer to a structure (fixed-length string)
p | String | pointer to a null-terminated string
Misc. | Array |
Directive | Element | Meaning
---------------------------------------------------------------------------
@ | --- | moves to absolute position
X | --- | back up a byte
x | --- | null byte
provides a unified clone operation, for REXML::XPathParser to use across multiple Object types
Produces a shallow copy of obj—the instance variables of obj are copied, but not the objects they reference. clone copies the frozen (unless :freeze keyword argument is given with a false value) state of obj. See also the discussion under Object#dup.
class Klass attr_accessor :str end s1 = Klass.new #=> #<Klass:0x401b3a38> s1.str = "Hello" #=> "Hello" s2 = s1.clone #=> #<Klass:0x401b3998 @str="Hello"> s2.str[1,4] = "i" #=> "i" s1.inspect #=> "#<Klass:0x401b3a38 @str=\"Hi\">" s2.inspect #=> "#<Klass:0x401b3998 @str=\"Hi\">"
This method may have class-specific behavior. If so, that behavior will be documented under the #initialize_copy method of the class.
Returns the receiver.
string = "my string" string.itself.object_id == string.object_id #=> true
Invokes the method identified by symbol, passing it any arguments specified. You can use __send__ if the name send clashes with an existing method in obj. When the method is identified by a string, the string is converted to a symbol.
BasicObject implements __send__, Kernel implements send.
class Klass def hello(*args) "Hello " + args.join(' ') end end k = Klass.new k.send :hello, "gentle", "readers" #=> "Hello gentle readers"
Returns an array with both a numeric and a big represented as Bignum objects.
This is achieved by converting numeric to a Bignum.
A TypeError is raised if the numeric is not a Fixnum or Bignum type.
(0x3FFFFFFFFFFFFFFF+1).coerce(42) #=> [42, 4611686018427387904]
provides a unified clone operation, for REXML::XPathParser to use across multiple Object types
Since int is already an Integer, this always returns true.
Iterates the given block, passing in integer values from int up to and including limit.
If no block is given, an Enumerator is returned instead.
5.upto(10) {|i| print i, " " } #=> 5 6 7 8 9 10
Iterates the given block int times, passing in values from zero to int - 1.
If no block is given, an Enumerator is returned instead.
5.times {|i| print i, " " } #=> 0 1 2 3 4
Returns the remainder after dividing int by numeric.
x.remainder(y) means x-y*(x/y).truncate.
5.remainder(3) #=> 2 -5.remainder(3) #=> -2 5.remainder(-3) #=> 2 -5.remainder(-3) #=> -2 5.remainder(1.5) #=> 0.5
See Numeric#divmod.