ruby基础用法简单整理
基础变量部分
- 变量声明
a = 10 a = "string"
- 支持并行赋值
a,b = 3,5 a,b = 3, "5"
a = b = 3
- 变量操作
a += 1
没有++操作符号
- 变量交换
a,b = 3,5
a,b = b,a #=> 5,3
- 语句后面不跟";"
a = 10
- ／
-5 / 2 #=> -3
-5.0/ 2 #=> -2.5
- ％
-5 % 2 #=> 1
-5 % 2.2 #=> 1.6
字符串
- 声明
str = "string"
- 切片操作
str[1...3] #=> "tr"
str[1,3] #=> "tri"
- 倒叙
str[-1] #=> "g"
- 字符串比较
if(str == sub) #=> true
- 字符替换
str[3] = "1" #=> "str1ng"
- 字符串*
str *3 #=> "stringstringstring"
- 字符串+
str + "s" #=> "str1ngs"
- 字符串长度
str.length str.size str.bytesize #=> 7
- 汉字
str = "人"
str.length str.size #=> 1
str.bytesize #=> 1
- 数字转字符串
str = "a is "
a = 10.0
str + a.to_s #=> "a is 10.0"
- 数组<<
str << "es" #=> stringes
str << ?5 #=> string5
str << 5 #=> string�
- 字符串内复值
sum = 5
str = "string #{sum}" #=> "string 5"
str = "string #{sum} is %d %s" % [5,"sum"] #=> "string 5 is 5 sum"
数组
- 声明
arr = [1,2,3,4]
other = 1,2,3,4
a,b,c = [1,2,3] #=> a = 1 b =2 c =3
a ,*b= [1,2,3,4] #=> a =1 b = [2,3,4]
*a ,b= [1,2,3,4] #=> a =[1,2,3] b = 4
- 支持多元数组
other = [1,2,3,4,"str"]
- 数组下标起始位置
arr[0] #=> 1
- 数组切片
sub = arr[1...3] #=> 1,2 ［1,3）
sub = arr[1,3] #=> 1,2,3 ［1, =>3长度
- 倒叙
arr[-1] #=> 4
- 数组比较
sub = [1,2,3,4]
if(arr == sub) #=> true
- 数组元素替换
arr[2] = "d" #=> [1,2,"d",4]
arr[1,3] = ["a","b"] #=> [1, "a", "b"]
- 数组*
arr * 3 #=> [1,2,3,4,1,2,3,4,1,2,3,4]
- 数组+
arr + [5] #=> [1,2,3,4,5]
arr + [[5,6]] #=> [1, 2, 3, 4, [5, 6]]
- 数组长度
arr.length arr.size #=> 74
- 数组= #=>两数组维持同一份拷贝
sub = arr #=> [1,2,3,4]
arr[2] = "d" sub #=> [1,2,d,4]
- Array数组深拷贝
sub = Array.new(arr)
if(sub == arr) #=> true
arr[2] = "d" sub #=> [1,2,3,4]
- 越界操作方式
arr[6] = 5 #=> [1, 2, 3, 4, nil, nil, 5]
- range对数组的初始化
('1'...'5').to_a #=> ["1", "2", "3", "4"]
- 切片赋值
arr[1...2] = ["a"] arr #=> [1, "a", 3, 4]
arr[1,2] = ["a"] arr #=> [1, "a", 4]
- 数组减法
sub = [1,2,3,4,5,6]
sub - arr #=> [5, 6]
- 数组<<
arr << 5 #=> [1, 2, 3, 4, 5]
- 数组&
sub = [1,3,5]
arr & sub #=> [1, 3]
- 数组|
sub = [1,3,5]
arr | sub #=> [1, 2, 3, 4, 5]
sub | arr #=> [1, 3, 5, 2, 4]
- 数组遍历
arr.each {|x| print x} #=> 1234
hash
- 初始化
nums = {:one=>1, :two=>2,:three=>3} #=> {:one=>1, :two=>2, :three=>3}
sums = hash.new
sums[1] = 1 #=> {1=>1}
sums = {"1"=>1, 2=>2} #=> {"1"=>1, 2=>2}
- 支持多元hash
nums = {:one=>1, :two=>"2"} #=> {:one=>1, :two=>"2"}
- 获取hash元素
nums[:one] #=> 1
- 元素替换
nums[:one] = 3 #=> {:one=>3, :two=>2}
- hash长度
nums.length nums.size #=> 3
range
- 初始化
range = 1..100 #=> 1..100
- include? && member? && cover? 判断
range.include?10.0 #=> true
range.include?10 #=> true
range.include?101.0 #=> false
符号
- respond_to?
class Greeter
def add x, y
x + y
end
end
gt = Greeter.new
gt.respond_to?:add #=> true
- string转符号
puts str.to_sym str.intern #=> add
- 符号转string
sign = :add
sign.to_sym sign.id2name #=> add
- instance_of? is_a? kind_of?
gt = Greeter.new
gt.instance_of? Greeter #=> true
gt.is_a? Greeter #=> true
gt.kind_of? Greeter #=> true
- class
gt.class #=> Greeter
- ==
a = "Ruby"
b = a
c = "Ruby"
a == b #=> true
a == c #=> true
a[1] = "3"
a== b #=> true
- equal?
a.equal?b #=> true
a.equal?c #=> false
a[1] = "3"
a.equal?b #=> true
- eql?
a.equal?b #=> true
a.equal?c #=> true
a[1] = "3"
a.eql?b #=> true
- <=>
1 <=> 3 #=> -1
3 <=> 3 #=> 0
4 <=> 3 #=> 1
条件式
- if条件
if a == b
"code"
end
if "expr"
"code"
elsif "expr"
"code"
else
"code"
end
if "expr" then
"code"
end
"code" if "expr" #不允许有elsif else 等从句
- unless
unless "expr"
"code"
end
"code" unless "expr" #不允许有elsif else 等从句
- case
case
when "expr" then "code"
when "expr" then "code"
when "expr" then "code"
else "many" then "code"
end
- until while
until "expr" do
"code"
end
"code" while "expr"
- for
for a in array
"code"
end
- times
3.times "code" #=>0,1,2
- each
data.each{|x| puts x}
- map
[1,2,3,4].map {|x| puts x}
- upto/downto
4.upto(7) { |x| print x} #=> 4567
- inject
sum = data.inject {|result , x| x +result} #=> 10
- yield
def five
yield 1,2,3,4,5
end
five do |x,*y,z|
print x #=> 1
print y #=> [2,3,4]
print z #=> 5
end
方法
- 函数
def func x
return x
end
- 多返回值
def func x
x
end
def func
return 1 , 2
end
def func
[1 , 2]
end
- 单键方法
o = "message"
def o.func x
x
end
- 可以定贷带问号结尾的函数
def empty
"code"
end
- 可以用变参
def max(first, *res)
max = first
res.each{
|x| max = x if x > max
}
max
end
puts max 1,2,3,4,5 #=> 5
- 默认参数
def sum x,y = 2,z = 3
x + y + z
end
- hash函数
def sequence args
n = args[:n]
m = args[:m]
c = args[:c]
a = []
n.times {|i| a << m*i+c}
a
end
puts sequence({:n=>3,:m=>5,:c=>1})
puts sequence :n=>3,:m=>5,:c=>1 (裸hash)
- 代码块
def sequence n ,m ,c
i = 0
while i < n
yield i * m + c
i+= 1
end
end
sequence(5,2,2) {|x| puts x } #=> 2,4,6,8,10
- proc对象
def makeProc &block
block
end
block = makeProc {|x| puts x }
block.call(3) #=> 3
- proc.new
block = Proc.new {|x| puts x }
block.call(3) #=> 3
- lambda表达式
lambda = ->x{puts x }
lambda.call(3) #=> 3
- lambda表达式默认参数
lambda = ->x =3{ y = x + 1; puts y }
lambda.call #=> 4
类
- 声明(类名必须大写否者报错)
class Point
def initialize(x,y)
@x,@y = x,y
end
def x; @x; end
def y; @y; end
def x=value; @x = value; end
def y=value; @y = value; end
end
p = Point.new 3,5
- 枚举坐标值
class Point
def initialize(x,y)
@x,@y = x,y
end
def each
yield @x
yield @y
end
end
p = Point.new 3,5
p.each {|x| print x} #=>3,5
- 定义==
def == o
if o.is_a?Point
@x ==o.x && @y == o.y
elsif
false
end
end
- 定义严格版eql?
def eql? o
if o.instance_of?Point
@x.eql?(o.x) && @y.eql?(o.y)
elsif
false
end
end
- 读写性
attr_reader :x,:y #=>只读
attr_accessor :x,:y #=>读写
- Struct方法创建类
Poi = Struct.new(:x,:y)
po = Poi.new(3,5)
puts po.x
- 拥有private,public,protected的类可见性
- 单例方法
o = Point.new 3,5
def o.sayBye
puts "byebye!"
end
o.sayBye #=> "byebye!"
- 单利方法的另外一种模式
class << o
def sayHi
puts "Hi"
end
end
- 单例方法查询
puts o.singleton_methods #=> sayBye
- 使用self定义的静态方法
class SelfTest
def self.test
puts "hello world selfTest."
end
end
SelfTest.test #=> "hello world selfTest."
- 使用类名定义的静态方法
class SelfTest
def SelfTest.test
puts "hello world selfTest."
end
end
SelfTest.test #=> "hello world selfTest."
- send调用方法
class Base
attr_accessor :x
def initialize x
@x = x
end
def add x ,y
x + y
end
end
o = Base.new 3
puts o.send(:add,3,7) #=> 10
- module
module Model
def sayHello
puts "hello world!"
end
end
class Base
include Model
def initialize x
@x = x
end
end
o = Base.new
o.sayHello #=> "hello world!"
反射，元编成
- class superclass 反射
class Base
attr_accessor :x
def initialize x
@x = x
end
def log
puts @x
end
end
o = Base.new 3
puts o.class #=> Base
puts o.class.superclass #=> Object
- eval求值
a = 100
puts eval "a + 1"
正则表达式
if "Ruby" =~ /[R,r]uby/
puts "true"
end
集合
- 遍历切片遍历
(1...10).each_slice(3) {|x| print x} #=> [1, 2, 3][4, 5, 6][7, 8, 9]
- 滑动切片遍历
(1...10).each_cons(3) {|x| print x} #=> [1, 2, 3][2, 3, 4][3, 4, 5][4, 5, 6][5, 6, 7][6, 7, 8][7, 8, 9]
