Ruby 数组用法
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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次
[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
查寻方法find,也有:list = ['a','b','c'] list.find{|x| x=='c'}
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") => 1
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 => 3
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") => 3
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nilargs = ["-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"
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