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Ruby數組

Ruby數組是有序的,任何對象的​​整數索引的集合。每個數組中的元素相關聯,並提到的一個索引。

數組下標從0開始,如C或Java。負數索引假設數組末尾---也就是說,-1表示最後一個元素的數組索引,-2是數組中最後一個元素的下一個元素等等。

Ruby的數組可以容納對象,如字符串,整數,長整數,哈希,符號,甚至其他Array對象。Ruby數組冇有在其他語言中數組一樣嚴格。Ruby數組自動增長同時增加元素。

創建數組:

有許多方法來創建或初始化一個數組。一種方式是 new 類方法:

names = Array.new

可以設置一個數組的大小,在數組創建的時候:

names = Array.new(20)

數組 names 現在有20個元素的大小或長度。您可以返回一個數組的大小尺寸或長度的方法:

#!/usr/bin/ruby

names = Array.new(20)
puts names.size  # This returns 20
puts names.length # This also returns 20

這將產生以下結果:

20
20

可以指定一個值數組中的每個元素如下:

#!/usr/bin/ruby

names = Array.new(4, "mac")

puts "#{names}"

這將產生以下結果:

macmacmacmac

還可以使用用new塊,塊會計算填充每個元素:

#!/usr/bin/ruby

nums = Array.new(10) { |e| e = e * 2 }

puts "#{nums}"

這將產生以下結果:

024681012141618

還有另一種方法,數組,[]。它的工作原理是這樣的:

nums = Array.[](1, 2, 3, 4,5)

另一種形式的數組創建如下:

nums = Array[1, 2, 3, 4,5]

內核模塊Ruby的核心,有一個數組的方法,隻接受一個參數。這裡的方法範圍內創建一個數組的數字作為參數:

#!/usr/bin/ruby

digits = Array(0..9)

puts "#{digits}"

這將產生以下結果:

0123456789

數組內置的方法:

我們需要有Array對象調用數組方法的一個實例。正如我們所看到的,下麵是Array對象的方式來創建一個實例:

Array.[](...) [or] Array[...] [or] [...]

這將返回一個新數組填充給定的對象。現在使用創建的對象,我們可以調用任何可用實例方法。例如:

#!/usr/bin/ruby

digits = Array(0..9)

num = digits.at(6)

puts "#{num}"

這將產生以下結果:

6

以下是公共數組方法(假設數組是一個數組對象):

SN 方法及描述
1 array & other_array
Returns a new array containing elements common to the two arrays, with no duplicates.
2 array * int [or] array * str
Returns a new array built by concatenating the int copies of self. With a String argument, equivalent to self.join(str).
3 array + other_array
Returns a new array built by concatenating the two arrays together to produce a third array.
4 array - other_array
Returns a new array that is a copy of the original array, removing any items that also appear in other_array.
5 str <=> other_str
Compares str with other_str, returning -1 (less than), 0 (equal), or 1 (greater than). The comparison is casesensitive.
6 array | other_array
Returns a new array by joining array with other_array, removing duplicates.
7 array << obj
Pushes the given object onto the end of array. This expression returns the array itself, so several appends may be chained together.
8 array <=> other_array
Returns an integer (-1, 0, or +1) if this array is less than, equal to, or greater than other_array.
9 array == other_array
Two arrays are equal if they contain the same number of elements and if each element is equal to (according to Object.==) the corresponding element in the other array.
10 array[index] [or] array[start, length] [or]
array[range] [or] array.slice(index) [or]
array.slice(start, length) [or] array.slice(range)

Returns the element at index, or returns a subarray starting at start and continuing forlength elements, or returns a subarray specified by range. Negative indices count backward from the end of the array (-1 is the last element). Returns nil if the index (or starting index) is out of range.
11 array[index] = obj [or]
array[start, length] = obj or an_array or nil [or]
array[range] = obj or an_array or nil

Sets the element at index, or replaces a subarray starting at start and continuing forlength elements, or replaces a subarray specified by range. If indices are greater than the current capacity of the array, the array grows automatically. Negative indices will count backward from the end of the array. Inserts elements if length is zero. If nil is used in the second and third form, deletes elements from self.
12 array.abbrev(pattern = nil)
Calculates the set of unambiguous abbreviations for the strings in self. If passed a pattern or a string, only the strings matching the pattern or starting with the string are considered.
13 array.assoc(obj)
Searches through an array whose elements are also arrays comparing obj with the first element of each contained array using obj.==. Returns the first contained array that matches , or nil if no match is found.
14 array.at(index)
Returns the element at index. A negative index counts from the end of self. Returns nil if the index is out of range.
15 array.clear
Removes all elements from array.
16 array.collect { |item| block } [or]
array.map { |item| block }

Invokes block once for each element of self. Creates a new array containing the values returned by the block.
17 array.collect! { |item| block } [or]
array.map! { |item| block }

Invokes block once for each element of self, replacing the element with the value returned by block.
18 array.compact
Returns a copy of self with all nil elements removed.
19 array.compact!
Removes nil elements from array. Returns nil if no changes were made.
20 array.concat(other_array)
Appends the elements in other_array to self.
21 array.delete(obj) [or] 
array.delete(obj) { block }

Deletes items from self that are equal to obj. If the item is not found, returns nil. If the optional code block is given, returns the result of block if the item is not found.
22 array.delete_at(index)
Deletes the element at the specified index, returning that element, or nil if the index is out of range.
23 array.delete_if { |item| block }
Deletes every element of self for which block evaluates to true.
24 array.each { |item| block }
Calls block once for each element in self, passing that element as a parameter.
25 array.each_index { |index| block }
Same as Array#each, but passes the index of the element instead of the element itself.
26 array.empty?
Returns true if the self array contains no elements.
27 array.eql?(other)
Returns true if array and other are the same object, or are both arrays with the same content.
28 array.fetch(index) [or] 
array.fetch(index, default) [or] 
array.fetch(index) { |index| block }

Tries to return the element at position index. If index lies outside the array, the first form throws an IndexError exception, the second form returns default, and the third form returns the value of invoking block, passing in index. Negative values of indexcount from the end of the array.
29 array.fill(obj) [or]
array.fill(obj, start [, length]) [or]
array.fill(obj, range) [or]
array.fill { |index| block } [or]
array.fill(start [, length] ) { |index| block } [or]
array.fill(range) { |index| block }

The first three forms set the selected elements of self to obj. A start of nil is equivalent to zero. A length of nil is equivalent to self.length. The last three forms fill the array with the value of the block. The block is passed the absolute index of each element to be filled.
30 array.first [or] 
array.first(n)

Returns the first element, or the first n elements, of the array. If the array is empty, the first form returns nil, and the second form returns an empty array.
31 array.flatten
Returns a new array that is a one-dimensional flattening of this array (recursively).
32 array.flatten!
Flattens array in place. Returns nil if no modifications were made. (array contains no subarrays.)
33 array.frozen?
Returns true if array is frozen (or temporarily frozen while being sorted).
34 array.hash
Compute a hash-code for array. Two arrays with the same content will have the same hash code
35 array.include?(obj)
Returns true if obj is present in self, false otherwise.
36 array.index(obj)
Returns the index of the first object in self that is == to obj. Returns nil if no match is found.
37 array.indexes(i1, i2, ... iN) [or]
array.indices(i1, i2, ... iN)

This methods is deprecated in latest version of Ruby so please use Array#values_at.
38 array.indices(i1, i2, ... iN) [or]
array.indexes(i1, i2, ... iN)

This methods is deprecated in latest version of Ruby so please use Array#values_at.
39 array.insert(index, obj...)
Inserts the given values before the element with the given index (which may be negative).
40 array.inspect
Creates a printable version of array.
41 array.join(sep=$,)
Returns a string created by converting each element of the array to a string, separated by sep.
42 array.last [or] array.last(n)
Returns the last element(s) of self. If array is empty, the first form returns nil.
43 array.length
Returns the number of elements in self. May be zero.
44 array.map { |item| block } [or]
array.collect { |item| block }

Invokes block once for each element of self. Creates a new array containing the values returned by the block.
45 array.map! { |item| block } [or]
array.collect! { |item| block }

Invokes block once for each element of array, replacing the element with the value returned by block.
46 array.nitems
Returns the number of non-nil elements in self. May be zero.
47 array.pack(aTemplateString)
Packs the contents of array into a binary sequence according to the directives in aTemplateString. 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 (_) to use the underlying platform's native size for the specified type; otherwise, they use a platformindependent size. Spaces are ignored in the template string. ( See templating Table below )
48 array.pop
Removes the last element from array and returns it, or nil if array is empty.
49 array.push(obj, ...)
Pushes (appends) the given obj onto the end of this array. This expression returns the array itself, so several appends may be chained together.
50 array.rassoc(key)
Searches through the array whose elements are also arrays. Compares key with the second element of each contained array using ==. Returns the first contained array that matches.
51 array.reject { |item| block }
Returns a new array containing the items array for which the block is not true.
52 array.reject! { |item| block }
Deletes elements from array for which the block evaluates to true, but returns nil if no changes were made. Equivalent to Array#delete_if.
53 array.replace(other_array)
Replaces the contents of array with the contents of other_array, truncating or expanding if necessary.
54 array.reverse
Returns a new array containing array's elements in reverse order.
55 array.reverse!
Reverses array in place.
56 array.reverse_each {|item| block }
Same as Array#each, but traverses array in reverse order.
57 array.rindex(obj)
Returns the index of the last object in array == to obj. Returns nil if no match is found.
58 array.select {|item| block }
Invokes the block passing in successive elements from array, returning an array containing those elements for which the block returns a true value.
59 array.shift
Returns the first element of self and removes it (shifting all other elements down by one). Returns nil if the array is empty.
60 array.size
Returns the length of array (number of elements). Alias for length.
61 array.slice(index) [or] array.slice(start, length) [or]
array.slice(range) [or] array[index] [or]
array[start, length] [or] array[range]

Returns the element at index, or returns a subarray starting at start and continuing forlength elements, or returns a subarray specified by range. Negative indices count backward from the end of the array (-1 is the last element). Returns nil if the index (or starting index) are out of range.
62 array.slice!(index) [or] array.slice!(start, length) [or]
array.slice!(range)

Deletes the element(s) given by an index (optionally with a length) or by a range. Returns the deleted object, subarray, or nil if index is out of range.
63 array.sort [or] array.sort { | a,b | block }
Returns a new array created by sorting self.
64 array.sort! [or] array.sort! { | a,b | block }
Sorts self.
65 array.to_a
Returns self. If called on a subclass of Array, converts the receiver to an Array object.
66 array.to_ary
Returns self.
67 array.to_s
Returns self.join.
68 array.transpose
Assumes that self is an array of arrays and transposes the rows and columns.
69 array.uniq
Returns a new array by removing duplicate values in array.
70 array.uniq!
Removes duplicate elements from self. Returns nil if no changes are made (that is, no duplicates are found).
71 array.unshift(obj, ...)
Prepends objects to the front of array, other elements up one.
72 array.values_at(selector,...)
Returns an array containing the elements in self corresponding to the given selector(one or more). The selectors may be either integer indices or ranges.
73 array.zip(arg, ...) [or] 
array.zip(arg, ...){ | arr | block }

Converts any arguments to arrays, then merges elements of array with corresponding elements from each argument.

數組包的指令:

下表列出了包指令使用 Array#pack.

Directive Description
@ Moves to absolute position.
A ASCII string (space padded, count is width).
a ASCII string (null padded, count is width).
B Bit string (descending bit order).
b Bit string (ascending bit order).
C Unsigned char.
c Char.
D, d Double-precision float, native format.
E Double-precision float, little-endian byte order.
e Single-precision float, little-endian byte order.
F, f Single-precision float, native format.
G Double-precision float, network (big-endian) byte order.
g Single-precision float, network (big-endian) byte order.
H Hex string (high nibble first).
h Hex string (low nibble first).
I Unsigned integer.
i Integer.
L Unsigned long.
l Long.
M Quoted printable, MIME encoding (see RFC 2045).
m Base64-encoded string.
N Long, network (big-endian) byte order.
n Short, network (big-endian) byte order.
P Yiibaier to a structure (fixed-length string).
p Yiibaier to a null-terminated string.
Q, q 64-bit number.
S Unsigned short.
s Short.
U UTF-8.
u UU-encoded string.
V Long, little-endian byte order.
v Short, little-endian byte order.
w BER-compressed integer fnm.
X Back up a byte.
x Null byte.
Z Same as a, except that null is added with *.

例如:

試試下麵的例子來收集各種數據。

a = [ "a", "b", "c" ]
n = [ 65, 66, 67 ]
puts a.pack("A3A3A3")   #=> "a  b  c  "
puts a.pack("a3a3a3")   #=> "a\000\000b\000\000c\000\000"
puts n.pack("ccc")      #=> "ABC"

這將產生以下結果:

a  b  c
abc
ABC