Ruby 数组（Array）

一、参数= 符号赋值数组对象 时，是指向同一个数组对象

eg:

1. irb(main):019:0> a = []   //定义一个数组
2. => []
3. irb(main):020:0> b = a   //将变量a赋值给b，a和b指向同个内存
4. => []
5. irb(main):021:0> a.object_id  //a的对象id
6. => 25204596
7. irb(main):022:0> b.object_id  //b的对象id
8. => 25204596
9. irb(main):023:0> a << 'foo'  //a写入值foo
10. => ["foo"]
11. irb(main):024:0> b  // 打印b的值发现和a一样
12. => ["foo"]

复制代码

二、界说数组的方法
1.[] 界说数组

1. irb(main):025:0> a = ['1','2']
2. => ["1", "2"]

复制代码

2.Array.new():括号中可以输入界说数组的长度，和数组的相同值，修改其中一个，其他值都改变，数组的参数都指向同一个对象

1. irb(main):026:0> Array.new(3)  //定义一个长度为3个的无数据的数组
2. => [nil, nil, nil]
3. irb(main):027:0> Array.new(3,"asdf") //定义有3个asdf 字符的数组
4. => ["asdf", "asdf", "asdf"]
5. irb(main):028:0> b =Array.new(3,"asdf")//定义有3个asdf 字符的数组并赋值给b
6. => ["asdf", "asdf", "asdf"]   
7. irb(main):029:0> b[0]  //b数组的第一参数的值
8. => "asdf"
9. irb(main):030:0> b[1]  //b数组的第二参数的值
10. => "asdf"
11. irb(main):031:0> b[0].object_id //b数组的第一参数对象的值
12. => 25986720
13. irb(main):032:0> b[1].object_id //b数组的第二参数对象的值
14. => 25986720
15. irb(main):033:0> b[0][2]='m'  //b数组的第二数据asdf 第三个字符d 改为m
16. => "m"
17. irb(main):034:0> b[0]
18. => "asmf"
19. irb(main):035:0> b[1]
20. => "asmf"
21. irb(main):036:0> b[2]
22. => "asmf"

复制代码

3.Array.new(){}:创建多个数组，值不一样，修改后不会都修改，可以修改指定值

1. irb(main):038:0> c = Array.new(2){'abcd'} //定义一个数组大小为2个，值都为abcd 的不同对象
2. => ["abcd", "abcd"]
3. irb(main):039:0> c[0]   //查看数组第一个的值
4. => "abcd"
5. irb(main):040:0> c[1]  //查看数组第二个的值
6. => "abcd"
7. irb(main):041:0> c[0].object_id  //查看数组第一个值的对象id
8. => 25344288
9. irb(main):042:0> c[1].object_id //查看数组第二个值的对象id
10. => 25344276
11. irb(main):043:0> c[1][2]='k'  //查看数组第二个值的字符串的第三个字符设置为k
12. => "k"
13. irb(main):044:0> c[0]  //查看数组第一个的值
14. => "abcd"
15. irb(main):045:0> c[1]  //查看数组第二个的值，可以看到只有第二个值改变了
16. => "abkd"

复制代码

3. %w(): 简朴快速的界说数组，不必要输入单引号和逗号

1. irb(main):046:0> arr = %w(aa bb cc dd)
2. => ["aa", "bb", "cc", "dd"]

复制代码

三、数组的方法
1.[]：查看第几个数据

1. irb(main):048:0> a = %w(foo bar wut wat) //定义数组
2. => ["foo", "bar", "wut", "wat"]
3. irb(main):049:0> a[0] //获取数组的第一个数据
4. => "foo"

复制代码

2.[..]：查看区间数据

1. irb(main):050:0> a[-1] //获取最后一个
2. => "wat"
3. irb(main):051:0> a[1..2]
4. => ["bar", "wut"]

复制代码

3.fetch():安全的取数据，可以界说取不到数据的情况

1. irb(main):052:0> a.fetch(2)
2. => "wut"
3. irb(main):053:0> a.fetch(4)
4. IndexError: index 4 outside of array bounds: -4...4
5.         from (irb):53:in `fetch'
6.         from (irb):53
7.         from D:/RailsInstaller/Ruby2.2.0/bin/irb:11:in `<main>'
8. irb(main):054:0> a.fetch(4,'asdf')
9. => "asdf"

复制代码

4.length

1. irb(main):055:0> a.length
2. => 4

复制代码

5.include?():数组是否包罗哪些字符

1. irb(main):057:0> a.include?('foo')
2. => true
3. irb(main):058:0> a.include?('aa')
4. => false

复制代码

6.empty?(): 是否为空数组

1. irb(main):059:0> a.empty?()
2. => false

复制代码

7.push():往数组后添加数据,也可以添加相同值

1. irb(main):060:0> a.push('haha')
2. => ["foo", "bar", "wut", "wat", "haha"]

复制代码

8.[]=:数组指定位置添加数据，如果中心没有数据，会创建空数据

1. irb(main):061:0> a[10]='aab'
2. => "aab"
3. irb(main):062:0> a
4. => ["foo", "bar", "wut", "wat", "haha", nil, nil, nil, nil, nil, "aab"]

复制代码

9.delete_at():删除指定位置的值

1. irb(main):062:0> a
2. => ["foo", "bar", "wut", "wat", "haha", nil, nil, nil, nil, nil, "aab"]
3. irb(main):063:0> a.delete_at(0)
4. => "foo"
5. irb(main):064:0> a
6. => ["bar", "wut", "wat", "haha", nil, nil, nil, nil, nil, "aab"]

复制代码

10.delete():删除指定内容的值

1. irb(main):064:0> a
2. => ["bar", "wut", "wat", "haha", nil, nil, nil, nil, nil, "aab"]
3. irb(main):065:0> a.delete('haha')
4. => "haha"
5. irb(main):066:0> a
6. => ["bar", "wut", "wat", nil, nil, nil, nil, nil, "aab"]

复制代码

11.uniq!: 相同值删除，保存其中一个,不加感叹号

1. irb(main):067:0> a.push('bar')
2. => ["bar", "wut", "wat", nil, nil, nil, nil, nil, "aab", "bar"]
3. irb(main):068:0> a.uniq()
4. => ["bar", "wut", "wat", nil, "aab"]

复制代码

12.shuffe: 将数组数据随机排序

1. irb(main):072:0> a.shuffle
2. => ["bar", "wut", "aab", "wat", nil]
3. irb(main):073:0> a
4. => ["bar", "wut", "wat", nil, "aab"]

复制代码

13.falttern:二维数组转为1维数组

1. irb(main):001:0> a=[[1,2,34],['a','b','c']]  //创建二维数组
2. => [[1, 2, 34], ["a", "b", "c"]]
3. irb(main):002:0> a.flatten  //将二维数组转为一维数组
4. => [1, 2, 34, "a", "b", "c"]

复制代码

四、遍历数组
1.each{}:遍历数组

1. irb(main):004:0> arr=['a','b','c','d'] //创建arr数组
2. => ["a", "b", "c", "d"]
3. irb(main):006:0> arr.each{|e| p e} //遍历打印数组，eg |e|为变量e  p为打印的意思 e为变量
4. "a"
5. "b"
6. "c"
7. "d"
8. => ["a", "b", "c", "d"]

复制代码

2.reverse_each{}: 倒序遍历数组

1. irb(main):004:0> arr=['a','b','c','d']
2. => ["a", "b", "c", "d"]
3. irb(main):007:0> arr.reverse_each{|e| p e} //倒序打印arr数组
4. "d"
5. "c"
6. "b"
7. "a"
8. => ["a", "b", "c", "d"]

复制代码

3.each_with_index: 下标遍历数组

1. irb(main):001:0> arr=['a','b','c','d']
2. => ["a", "b", "c", "d"]
3. irb(main):002:0> arr.each_with_index{|e,i| p [e,i]}   //定义e和i变量，e为数组数据，i为数组的下标
4. ["a", 0]
5. ["b", 1]
6. ["c", 2]
7. ["d", 3]
8. => ["a", "b", "c", "d"]

复制代码

4.sort:数组数据从小到大排序

1. irb(main):003:0> arr=[-1,-2,-4,0,99,-2,8]
2. => [-1, -2, -4, 0, 99, -2, 8]
3. irb(main):004:0> arr.sort
4. => [-4, -2, -2, -1, 0, 8, 99]

复制代码

5.select{}:遍历判定数组的值

1. irb(main):003:0> arr=[-1,-2,-4,0,99,-2,8]
2. => [-1, -2, -4, 0, 99, -2, 8]
3. irb(main):005:0> arr.select{|e| e>0}  //数组元素大于0的数据
4. => [99, 8]

复制代码

6.compact: 删除数组里面空元素

1. irb(main):006:0> arr<< nil
2. => [-1, -2, -4, 0, 99, -2, 8, nil]
3. irb(main):007:0> arr.compact  //删除nil 空白元素，ps要想对arr生效，可以用危险！eg:arr.compact!
4. => [-1, -2, -4, 0, 99, -2, 8]
5. irb(main):008:0> arr
6. => [-1, -2, -4, 0, 99, -2, 8, nil]
7. irb(main):009:0> arr.compact!
8. => [-1, -2, -4, 0, 99, -2, 8]
9. irb(main):010:0> arr
10. => [-1, -2, -4, 0, 99, -2, 8]

复制代码

7.any?{}: 是否含有{条件}。eg：是否含有小于 零的数

1. irb(main):010:0> arr
2. => [-1, -2, -4, 0, 99, -2, 8]
3. irb(main):011:0> arr.any?{|e| e<0}  //数组是否含有小于0的元素
4. => true

复制代码

更多array利用：https://ruby-doc.org//core-2.2.0/Array.html
课后训练
输入：input=[1,2,3]  输出：output = [2,4,6]
要求：
不能改变原input
output 是一个新的array object
尽量简便

1. output= []
3. input.each{|e| output << e*2}

复制代码

免责声明：如果侵犯了您的权益，请联系站长，我们会及时删除侵权内容，谢谢合作！更多信息从访问主页：qidao123.com:ToB企服之家，中国第一个企服评测及商务社交产业平台。