ruby基礎用法簡單整理

基礎變量部分

1. 變量聲明

a = 10  a = "string"

2. 支持并行賦值

a,b = 3,5   a,b = 3, "5"
a = b = 3

3. 變量操作

a += 1
 沒有++操作符號

4. 變量交換

a,b = 3,5
a,b = b,a     #=> 5,3

5. 語句后面不跟";"

a = 10

6. ／

 -5 / 2           #=> -3
 -5.0/ 2          #=> -2.5

7. ％

-5 % 2      #=> 1
-5 % 2.2    #=> 1.6

字符串

1. 聲明

str = "string"

2. 切片操作

 str[1...3] #=> "tr"
 str[1,3] #=> "tri"

3. 倒敘

str[-1] #=> "g"

4. 字符串比較

 if(str == sub)   #=> true

5. 字符替換

str[3] = "1" #=> "str1ng"

6. 字符串*

str *3 #=> "stringstringstring"

7. 字符串+

str + "s" #=> "str1ngs"

8. 字符串長度

str.length  str.size str.bytesize #=> 7

9. 漢字

str = "人"   
str.length  str.size    #=> 1
str.bytesize            #=> 1

10. 數(shù)字轉字符串

str = "a is "
a = 10.0
str + a.to_s    #=> "a is 10.0"

11. 數(shù)組<<

str << "es"   #=> stringes
str << ?5     #=> string5
str << 5      #=> string?</pre>

12. 字符串內(nèi)復值

sum = 5
str = "string #{sum}"   #=>  "string 5"
str = "string #{sum}  is %d %s" % [5,"sum"]    #=> "string 5  is 5 sum"</pre>

數(shù)組

1. 聲明

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

2. 支持多元數(shù)組

other = [1,2,3,4,"str"]

3. 數(shù)組下標起始位置

arr[0] #=> 1

4. 數(shù)組切片

sub = arr[1...3]      #=>  1,2  ［1,3）
sub = arr[1,3]      #=>  1,2,3  ［1, =>3長度

5. 倒敘

arr[-1] #=> 4

6. 數(shù)組比較

sub = [1,2,3,4]
if(arr == sub)   #=> true

7. 數(shù)組元素替換

arr[2] = "d"  #=> [1,2,"d",4]
arr[1,3] = ["a","b"]   #=> [1, "a", "b"]

8. 數(shù)組*

arr * 3 #=> [1,2,3,4,1,2,3,4,1,2,3,4]

9. 數(shù)組+

 arr + [5] #=> [1,2,3,4,5]
 arr + [[5,6]] #=> [1, 2, 3, 4, [5, 6]]

10. 數(shù)組長度

arr.length  arr.size  #=> 74

11. 數(shù)組= #=>兩數(shù)組維持同一份拷貝

sub = arr            #=> [1,2,3,4]
arr[2] = "d" sub    #=> [1,2,d,4]

12. Array數(shù)組深拷貝

 sub = Array.new(arr)
 if(sub == arr) #=> true
 arr[2] = "d"  sub #=> [1,2,3,4]

13. 越界操作方式

arr[6] = 5  #=> [1, 2, 3, 4, nil, nil, 5]

14. range對數(shù)組的初始化

 ('1'...'5').to_a #=> ["1", "2", "3", "4"]

15. 切片賦值

arr[1...2] = ["a"]  arr #=> [1, "a", 3, 4]
arr[1,2] = ["a"]  arr #=> [1, "a", 4]

16. 數(shù)組減法

sub = [1,2,3,4,5,6]
sub - arr    #=> [5, 6]

17. 數(shù)組<<

 arr << 5   #=> [1, 2, 3, 4, 5]

18. 數(shù)組&

sub = [1,3,5]
arr & sub   #=> [1, 3]

19. 數(shù)組|

sub = [1,3,5]
arr | sub       #=> [1, 2, 3, 4, 5]
sub | arr       #=> [1, 3, 5, 2, 4]

20. 數(shù)組遍歷

 arr.each {|x| print x}     #=>  1234

hash

1. 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}

2. 支持多元hash

nums = {:one=>1, :two=>"2"}    #=>  {:one=>1, :two=>"2"}

3. 獲取hash元素

nums[:one]     #=> 1

4. 元素替換

nums[:one] = 3  #=> {:one=>3, :two=>2}

5. hash長度

 nums.length  nums.size  #=> 3

range

1. 初始化

 range = 1..100  #=> 1..100

2. include? && member? && cover? 判斷

range.include?10.0      #=> true
range.include?10        #=> true
range.include?101.0     #=> false

符號

1. respond_to?

class Greeter
    def add x, y
        x + y
    end
 end
 
gt = Greeter.new 
gt.respond_to?:add      #=> true

2. string轉符號

puts str.to_sym  str.intern     #=> add

3. 符號轉string

sign = :add
sign.to_sym     sign.id2name    #=> add

4. instance_of? is_a? kind_of?

gt = Greeter.new
gt.instance_of? Greeter     #=> true
gt.is_a? Greeter            #=> true
gt.kind_of? Greeter         #=> true

5. class

gt.class #=> Greeter

6. ==

a = "Ruby"
b = a
c = "Ruby"
 
a == b      #=> true
a == c      #=> true
a[1] = "3"
a== b       #=> true

7. equal?

a.equal?b       #=> true
a.equal?c       #=> false

a[1] = "3"
a.equal?b       #=> true

8. eql?

a.equal?b       #=> true
a.equal?c       #=> true
   
a[1] = "3"
a.eql?b         #=> true

9. <=>

1 <=> 3     #=> -1
3 <=> 3     #=> 0
4 <=> 3     #=> 1

條件式

1. if條件

 if a == b
    "code"
 end 

 if "expr"
    "code"
 elsif "expr"
    "code"
 else
     "code"
 end

 if "expr" then
     "code"
 end

 "code" if  "expr"   #不允許有elsif else 等從句

2. unless

unless "expr" 
    "code"
  end 

  "code" unless  "expr"   #不允許有elsif else 等從句

3. case

 case
   when "expr" then "code"
   when "expr" then "code"
   when "expr" then "code"
   else "many" then "code"
 end

4. until while

 until "expr" do
    "code"
 end

 "code" while "expr"

5. for

for a in array 
    "code"
 end 

6. times

3.times "code"  #=>0,1,2

7. each

 data.each{|x| puts x}

8. map

 [1,2,3,4].map {|x| puts x}

9. upto/downto

4.upto(7) { |x| print x}   #=> 4567

10. inject

sum = data.inject {|result , x| x +result} #=> 10

11. 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

1. 函數(shù)

def func x
    return x
end

2. 多返回值

def func x
    x
 end

 def func
    return 1 , 2
 end

 def func
    [1 , 2]
 end

3. 單鍵方法

o = "message"
 def o.func x
    x
 end

4. 可以定貸帶問號結尾的函數(shù)

def empty
    "code"
 end

5. 可以用變參

def max(first, *res)
    max = first
    res.each{
      |x| max = x if x > max
    }
    max
 end
 puts max 1,2,3,4,5  #=> 5

6. 默認參數(shù)

def sum x,y = 2,z = 3
    x + y + z
 end

7. hash函數(shù)

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)

8. 代碼塊

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

9. proc對象

def makeProc &block
    block
 end

 block = makeProc {|x| puts x }  
 block.call(3)                     #=> 3

10. proc.new

block = Proc.new {|x| puts x }
block.call(3)                     #=> 3

11. lambda表達式

lambda = ->x{puts x }
lambda.call(3)                    #=> 3

12. lambda表達式默認參數(shù)

lambda = ->x =3{ y = x + 1; puts y }
lambda.call           #=> 4

類

1. 聲明(類名必須大寫否者報錯)

 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

2. 枚舉坐標值

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

3. 定義==

def == o
    if o.is_a?Point
      @x ==o.x && @y == o.y
    elsif
      false
    end
 end

4. 定義嚴格版eql?

 def eql? o
    if o.instance_of?Point
      @x.eql?(o.x) && @y.eql?(o.y)
    elsif 
      false
    end
 end

5. 讀寫性

attr_reader :x,:y  #=>只讀
attr_accessor :x,:y  #=>讀寫

6. Struct方法創(chuàng)建類

 Poi = Struct.new(:x,:y)
 po = Poi.new(3,5)
 puts po.x

7. 擁有private,public,protected的類可見性

8. 單例方法

o = Point.new 3,5
 def o.sayBye
    puts "byebye!"
 end

 o.sayBye   #=> "byebye!"

9. 單利方法的另外一種模式

class << o
    def sayHi
      puts "Hi"
    end
 end

10. 單例方法查詢

puts o.singleton_methods  #=> sayBye

11. 使用self定義的靜態(tài)方法

class SelfTest
    def self.test
      puts "hello world selfTest."
    end
 end

 SelfTest.test  #=> "hello world selfTest."</pre>

12. 使用類名定義的靜態(tài)方法

class SelfTest
    def SelfTest.test
      puts "hello world selfTest."
    end
  end

  SelfTest.test  #=> "hello world selfTest."

13. send調(diào)用方法

<pre>  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

14. 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!"</pre>

反射，元編成

1. 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</pre>

2. eval求值

 a = 100
 puts eval "a + 1"

正則表達式

if "Ruby" =~ /[R,r]uby/
  puts "true"
end

集合

1. 遍歷切片遍歷

 (1...10).each_slice(3) {|x| print x} #=> [1, 2, 3][4, 5, 6][7, 8, 9]

2. 滑動切片遍歷

 (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]