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Ruby的数组方法  


函数名称

说明

示例

&     

                        

数组与,返回两数组的交集      

[1,2] & [2,3] » [2]                                               

*

 

复制数组n

[1,2]*2       » [1,2,1,2]

+

 

返回两数组的并集,但不排除重复元素

[1,2]+[2,3]    » [1,2,2,3]

<< 

 

追加元素,但不排除重复元素

[1,2]<<[2,3]   » [1,2,2,3]

|

 

追加元素,但排除重复元素

[1,2] | [2,3]    » [1,2,3]

-

 

返回第一个数组与第二个数组不同的元素

[1,2]-[2,3]    » [1]

<=>

 

比较数组

[1,2]<=>[2,3] »flase

==

 

比较数组,若所有元素均相等时返回真

[1,2]==[2,1]    »flase

assoc

 

从数组的每个元素中寻找指定对象

[[1,2],[3,4]].assoc(2) » [1,2]

at

找到数组的第N个元素

 

负数表示逆向查找

["a","b","c","d","e"].at(0) » "a"

 

["a","b","c","d","e"].at(-1)  » "e"

clear

 

删除数组中的所有元素

["a","b","c","d","e"]. clear

collect

 

collect

 

用一个过程块对数组的每个元素进行处理

["a","b","c","d"].collect {|x| x + "!" } 

» ["a!", "b!", "c!", "d!"] 

compact

 

compact!

 

删除值为nil的元素后生成新数组并返回它

["a",nil,"b",nil,"c",nil].compact 

 

» ["a", "b", "c"] 

delete

 

删除元素,如果元素重复,全部删除

a = [ "a", "b", "b", "b", "c" ] 

 

a.delete("b")

 

puts a    » ["a","c"]

delete_at

删除pos所指位置的元素并返回它。若pos超出数

组范围则返回nil

a = %w( ant bat cat dog ) 

 

a.delete_at(2)   » "cat" 

 

a» ["ant", "bat", "dog"] 

 

a.delete_at(99)  » nil

 

delete_if

 

根据条件删除

a = [ "a", "b", "c" ] 

 

a.delete_if {|x| x >= "b" } » ["a"] 

each

对数组的每个元素按值进行迭代操作

a = [ "a", "b", "c" ]

 

a.each {|x| print x, " -- " }

 

 »  "a -- b -- c --"

each_index

对数组的每个元素按索引进行迭代操作

a = [ "a", "b", "c" ]

a.each_index {|x| print x, " -- " }

» "0 -- 1 -- 2 --"

empty?

判断数组是否为空,为空则返回真

[].empty? » true 

eql

比较两数组是否相等

["a","b","c"].eql?(["a","b","c"]) » true 

fill

填充数组

["a","b","c","d"].fill("x") 

» ["x","x","x","x"] 

["a","b","c","d"].fill("z", 2, 2) 

» ["x", "x", "z", "z"]

first

返回数组的首元素。若没有首元素则返回nil

[ "q", "r", "s", "t" ].first    » "q"

last

返回数组末尾的元素。若数组为空时,返回nil

["w","x","y","z"].last      » "z" 

include?

判断数组中是否包含元素

a = [ "a", "b", "c" ] 

a.include?("b") » true 

a.include?("z") » false

index

返回数组中第一个==val的元素的位置

a = [ "a", "b", "c" ] 

a.index("b") »

a.index("z") » nil 

indexes

以数组形式返回其索引值与各参数值相等的元素

a = [ "a", "b", "c", "d", "e", "f", "g" ] 

a.indexes(0, 2, 4)     » ["a", "c", "e"] 

a.indexes( 2, 4, 12)    » [ "c", "e", nil] 

insert

在索引为nth的元素前面插入第2参数以后的值

ary = %w(foo bar baz)

ary.insert 2,'a','b'

p ary   » ["foo", "bar", "a", "b", "baz"]

join

将数组元素按一定的分隔符连接起来

[ "a", "b", "c" ].join » "abc" 

[ "a", "b", "c" ].join("-") » "a-b-c" 

length

size

返回数组长度。若数组为空则返回0

[1,2,3].length     » 3

[1,2,3].size       » 3

nitems

返回非nil元素的个数

[ 1, nil, 3, nil, 5 ].nitems »

pop

删除末尾元素并返回它。若数组为空则返回nil

a = [ "a", "m", "z" ] 

a.pop               » "z" 

p a                 » ["a", "m"] 

push

添加新元素

["a","b"].push(['1','2'])

» ["a", "b", ["1", "2"]]

rassoc

遍历数组每个元素(元素必须是数组),匹配索引为1的值是否与查找的字符相等,返回第一个相等的元素

a = [[15,1], [25,2], [35,2]]

p a.rassoc(2)           » [25, 2]

replace

替换数组元素

a = ["a","b"] 

a.replace(["x","y","z"])  

p a                    »["x", "y", "z"] 

reverse

reverse

将所有元素以逆序重新排列生成新数组并返回它

["a","b","c" ].reverse » ["c", "b", "a"]

rindex

返回最后一个值相等的元素的索引值

a = [ "a","b","b","b","c"] 

a.rindex("b")              »

shift

删除数组的首元素并返回它。剩余元素依次提前。若数组为空返回nil

args = ["-m","-q","filename"] 

args.shift » "-m" 

args » ["-q", "filename"] 

sort

sort!

从小到大排序

a = [ "d", "a", "e", "c", "b" ] 

a.sort   » ["a", "b", "c", "d", "e"] 

uniq

uniq

删除数组中的重复元素后生成新数组并返回它

a = [ "a", "a", "b", "b", "c" ] 

a.uniq      » ["a", "b", "c"] 

unshift

在数组第一个元素前添加元素

a = [ "b", "c", "d" ] 

a.unshift("a")   » ["a", "b", "c", "d"] 

to_s

将数组的所有元素连接成字符串

["a","e","i","o"].to_s     » "aeio"