Ruby語言學習系列--基本的ruby語法
1. 基本的ruby語法
1.1 變量、常量和類型
1) 定義變量
變量類型
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描述
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示例
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局部變量(或僞變量)
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以小寫字母或下劃線卡頭
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var _var
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全局變量
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以$開頭
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$var
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類變量
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類中定義,以@@開頭
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@@var
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實例變量
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對象中定義,以@開頭
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@var
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常量
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以大寫字母開頭
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Var
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2) 變量內插
在雙引號內使用“#{變量名}”內插變量
a = 2
b = 3
puts "#{a} + #{b} = #{a+b}" #輸入結果爲:2 + 3 = 5
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1.2 註釋
1)單行註釋:以#開頭,如: #註釋內容
2)多行註釋:在=begin 和 =end 之間定義,如:
=begin
註釋內容
=end
1.3 循環和分支
1.3.1 條件語句
If 形式
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unless 形式
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a =1 if y==3
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a=1 unless y!=3
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x= if a > 0 then b else c end
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x= unless a<=0 then a else b end
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if x<5 then
a =1
else
a =2
end
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unless x<5 then
a =2
else
a =1
end
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1.3.2 循環結構
#while循環
i= 0
while i< list.size do
print “#list ”
I += 1
end
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#until循環
i= 0
until i == list.size do
print “#list”
i += 1
end
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#for循環
for x in lisy do
print “#{x}”
end
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#each循環
list.each do |x|
print “#{x}”
end
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#loop循環
i = 0
n = list.size-1
loop do
print “#{list}”
i += 1
break id i > n
end
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#times循環
n = list.size
n.times do |i|
print “#{list}”
end
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#upto循環
n =list.size–1
0.upto(n) do |i|
print “#{list}”
end
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#each_index循環
list.each_index do |x|
print “#{list[x]}”
end
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1.3.3 異常
begin
x = Math.sqrt(y/z)
rescue ArgumentError #匹配錯誤類型
puts "Error taking square root"
rescue ZeroDivisionError #匹配錯誤類型
puts "Attempted division by zero"
else
puts "Other Error"
ensure
#這部分代碼在最後一定會執行
end
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1.3.4 類
class Hello #類名必須以大寫字母開頭
@@myname = "John" #類變量
def initialize(name,phone)
@name,@phone = name,phone #定義實例變量
end
def hello #定義類方法
puts "#{@name}的電話是#{@phone}"
end
end
f = Hello.new("Tom","13100000000") #創建類對象
f.hello #調用類方法,結果爲:Tom的電話是13100000000
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1.3.5 模塊
方法
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說明
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include ‘watir’
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將模塊的功能添加到當前空間中,不加載已加載的文件
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extend ‘watir’
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將模塊的函數添加到對象中
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load ‘watir’
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讀取文件,並將其插入到源文件的當前位置,以便從這個位置開始就可以使用其定義
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1.3.6 case語句
case x
when 1..10 #匹配數字
puts "First branch"
when foobar() #批量方法返回的值
puts "Second branch"
when /^hel.*/ #匹配正則表達式
puts "Third branch"
else
puts "Last branch"
end
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Ruby語言學習系列--String 類函數
函數名稱
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說明
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示例
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*
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將字符串拷貝N次
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“ha”*4 >> “hahahaha”
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+
<<
concat
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連接字符串
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“yes” + “no” >> “yesno”
"yes" << "no" >> “yesno”
"yes".concat("no")
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<=>
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比較字符串,返回值如下:
大於:-1 等於:0 小於:1
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"Ab" <=> "ab" >> -1
"ab" <=> "ab" >> 0
"ab" <=> "Ab" >> 1
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== 或 ===
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判斷兩個對象是否相等
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"1" == "1" >>true
"1" == 1 >>flase
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=~
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匹配正則表達式
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"abc123abc" =~ /"d/ >> 3
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[ ] 或 slice
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返回字符串的某一範圍內的值
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“abc”[0,2] >> “ab”
"hello"[/llo/] >> “llo”
“abc” slice [0,2] >> “ab”
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[ ]=
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替換字符串的某一範圍內的值
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a = “hello word”
a[1,2]= “OO”
puts a >>” hOOlo word”
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capitalize
capitalize!
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把字符串的首字母大寫,其他字母小寫
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"hi,Ruby".capitalize
>> “Hi,ruby”
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chomp
chomp!
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刪除字符串後的空白字符
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"string"r"n".chomp
>> ” string”
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chop
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刪除最後一個字符
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"string".chop >> “strin”
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count
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返回該字符串中含的字符個數
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a = "hello world"
a.count "lo" >> 5
(l出現 3次,o出現 2次)
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delete
delete!
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刪除字符
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"hello".delete "l","lo" » "heo"
"hello".delete "lo" » "he"
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downcase
downcase!
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將大寫字母改寫爲小寫
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"hEllO".downcase » "hello"
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upcase
upcase!
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將小寫字母改寫爲大寫
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"hEllO".upcase » "HELLO"
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swapcaseswapcase!
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將所有的大寫字母改爲小寫字母,
小寫字母改爲大寫字母。
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"Hello".swapcase » "hELLO"
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each
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對字符串中的各行進行迭代操作
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"Hi"nRuby". each { |s| puts s}
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each_byte
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對字符串中的各個字節進行迭代操作
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"Hi"nRuby". each_byte { |s| puts s}
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each_line
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對字符串中的每一行進行迭代操作
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"Hi"nRuby". each_line { |s| puts s}
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empty?
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判斷字符串是否爲空
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"hello".empty? » false
"".empty? » true
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gsub
gsub!
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以replace來替換字符串中所有與pattern相匹配的部分
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"hello".gsub(/[aeiou]/, '*') » "h*ll*"
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hash
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返回字符串的哈希值
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"h".hash >> 107
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include?
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若字符串中包含substr子字符串的話,就返回真
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"hello".include? "lo" » true
"hello".include? "ol" » false
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index
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按照從左到右的順序搜索子字符串,並返回搜索到的子字符串的左側位置. 若沒有搜索到則返回nil
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"hello".index('lo') » 3
"hello".index('a') » nil
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length
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返回字符串的字節數
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"hello".length >> 5
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replace
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替換字符串的內容
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s = "hello" » "hello"
s.replace "world" » "world"
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sub 或 sub!
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用replace來替換首次匹配pattern的部分。
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"hello".sub(/[aeiou]/, '*')
» "h*llo"
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reverse
reverse!
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對字符串進行反轉
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"stressed".reverse » "desserts"
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scan
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使用正則表達式re反覆對self進行匹配操作,並以數組的形式返回匹配成功的子字符串
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a = "cruel world"
a.scan(/"w+/) » ["cruel", "world"]
a.scan(/.../) » ["cru", "el ", "wor"]
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split
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使用sep指定的pattern來分割字符串,並將分割結果存入數組
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"mellow yellow".split("ello")
» ["m", "w y", "w"]
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squeeze
squeeze!
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壓縮由str所含字符構成的重複字符串
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"yellow moon".squeeze
» "yelow mon"
" now is the".squeeze(" ")
» " now is the"
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strip
strip!
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刪除頭部和尾部的所有空白字符。空白字符是指" "t"r"n"f"v"。
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" hello ".strip » "hello"
""tgoodbye"r"n".strip » "goodbye"
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tr 或tr!
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若字符串中包含search字符串中的字符時,就將其替換爲replace字符串中相應的字符
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hello".tr('aeiou', '*') » "h*ll*"
"hello".tr('^aeiou', '*') » "*e**o"
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tr_s 或tr_s!
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若字符串中包含search字符串中的字符時,就將其替換爲replace字符串中相應的字符。同時,若替換部分中出現重複字符串時,就將其壓縮爲1個字符
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"hello".tr_s('l', 'r') » "hero"
"hello".tr_s('el', '*') » "h*o"
"hello".tr_s('el', 'hx') » "hhxo"
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upto
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在從self到max的範圍內,依次取出下一個字符串”後將其傳給塊,進行迭代操作
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"a1".upto("a3") {|s| puts s}
» a1"na2"na3
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to_f
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將字符串轉爲浮點數
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"45.67 degrees".to_f » 45.67
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to_i
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將字符串轉爲整數
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"99 red balloons".to_i » 99
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to_s
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將字符串轉爲字符串
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ruby學習系列--Hash類函數
函數名稱
|
說明
|
示例
|
==
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判斷兩個Hash是否相等
|
h1 = {"a" => 1, "c" => 2}
h2 = { "a" => 1, "c" => 2, 7 => 35 }
h1 == h2 » false
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[ ]
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返回指定鍵值對應的對象
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h = { "a" => 100, "b" => 200 }
h["a"] » 100
h["c"] » nil
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[ ]=
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向Hash添加記錄
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h = { "a" => 100, "b" => 200 }
h["a"] = 9
h["c"] = 4
h » {"a"=>9, "b"=>200, "c"=>4}
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clear
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清空哈希表的內容. 返回self.
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h = { "a" => 100, "b" => 200 }
h.clear » {}
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default
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返回哈希表的默認值
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h = { "a" => 100, "b" => 200 }
h.default = "Go fish"
h["a"] » 100
h["z"] » "Go fish"
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delete
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從詞典中刪除和鍵值相符的記錄
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h = { "a" => 100, "b" => 200 }
h.delete("a") » 100
h.delete("z") » nil
h.delete("z") { |el| "#{el} not found" } » "z not found"
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delete_if
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通過過程塊來刪除特定鍵值的記錄
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h = { "a" => 100, "b" => 200 }
h.delete_if {|key, value| key >= "b" }
» {"a"=>100}
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each
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Hash表的迭代操作,對錶的每一個詞對進行迭代操作
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h = { "a" => 100}
h.each {|key, value| print key, " is ",value,""n"} » a is 100
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each_key
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對錶的每一個鍵對進行迭代操作
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h = { "a" => 100, "b" => 200 }
h.each_key {|key| print key } » ab
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each_value
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針對value進行迭代操作
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h = { "a" => 100, "b" => 200 }
h.each_value {|value| print value }
» 100200
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empty?
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判斷哈希表是否爲空,空則返回true
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{}.empty? » true
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fetch
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如果能找到鍵值爲key的hash值,則返回Hash值;
如果找不到,則返回默認值或指定值;
如果默認值和指定值都找不到,拋異常
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h = { "a" => 100, "b" => 200 }
h.fetch("a") » 100
h.fetch("z", "go fish") » "go fish"
h.fetch("k")
»in `fetch': key not found (IndexError)
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has_key?
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判斷是否存在相符的key值
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h = { "a" => 100, "b" => 200 }
h.has_key?("a") » true
h.has_key?("z") » false
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key?
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h. key?("z") » false
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include?
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h.include?("b") » true
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has_value?
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判斷是否存在相符的value值
|
h = { "a" => 100, "b" => 200 }
h.has_value?(100) » true
h.has_value?(999) » false
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value?
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h.value?(100) » true
h.value?(999) » false
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index
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返回給定值的鍵值,未找到返nil
|
h = { "a" => 100, "b" => 200 }
h.index(200) » "b"
h.index(999) » nil
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indexes
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返回一系列給定的鍵值對應值組成的數組
|
h = { "a" =>100, "b" =>200, "c" =>300 }
h.indexes("a", "c") » [100,300]
h.indexes("a","z") » [100,nil]
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indices
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h.indexes("a", "c") » [100,300]
h.indexes("a", "z") » [100,nil]
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invert
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將元素值和索引互換,返回變換後的哈希表.
注意:若原哈希表中若干不同的索引對應相同的元素值時,其變換結果將無法預測.
|
h = { "n" => 100,"m" => 100,"y" => 300}
h.invert » {300=>"y",100=>"n"}
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keys
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返回一個包含所有key的數組.
|
h = { "a" => 100, "b" => 200 }
h.keys » ["a", "b"]
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values
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返回一個包含所有vakue的數組.
|
h = { "a" => 100,"b" => 200,"c" => 300 }
h.values » [100, 200, 300]
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length
|
返回詞典中元素的個數
|
h = { "d" =>100, "a"=> 200, "v" => 300}
h.length » 3
h. size » 3
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size
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rehash
|
重新計算索引對應的哈希表值。
當與索引對應的哈希表值發生變化時,若不使用該方法來重新計算的話,將無法取出與索引對應的哈希表值。
|
a = [ "a", "b" ]
c = [ "c", "d" ]
h = { a => 100, c => 300 }
a[0] = "z"
h.rehash
» {["z", "b"]=>100, ["c", "d"]=>300}
h[a] » 100
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replace
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以另外一張Hash表的內容來替換當前Hash表的內容
|
h = {"a" =>100, "b" =>200 }
h.replace({ "c" => 300, "d" => 400 })
» {"c"=>300, "d"=>400}
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shift
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刪除一個哈希表元素後
再以[key,value]數組的形式將其返回
|
h = { 1 => "a", 2 => "b", 3 => "c" }
h.shift » [1, "a"]
h » {2=>"b", 3=>"c"}
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sort
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對Hash進行排序
按鍵值從小到大排序
|
h = { "b" => 30, "a" => 20, "c" => 10 }
h.sort » [["a", 20], ["b", 30], ["c", 10]]
h.sort {|a,b| a[1]<=>b[1]}
» [["c", 10], ["a", 20], ["b", 30]]
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to_a
|
把Hash錶轉換爲數組
數組按Hash表的鍵值從小到大排序
|
h = {"c" =>300,"a" =>100,"d" =>400}
» [["a", 100], ["c", 300], ["d", 400]]
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to_s
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把Hash錶轉換爲字符串
|
h = { "c" => 300, "a" => 100, "d" => 400}
h.to_s » "a100c300d400"
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update
|
用一張Hash表去更新另外張Hash表
|
h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.update(h2)
» {"a"=>100, "b"=>254, "c"=>300}
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Ruby語言學習系列--Array類函數
函數名稱
|
說明
|
示例
|
&
|
數組與,返回兩數組的交集
|
[1,2] & [2,3] » [2]
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*
|
複製數組n次
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[1,2]*2 » [1,2,1,2]
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+
|
返回兩數組的並集,但不排除重複元素
|
[1,2]+[2,3] » [1,2,2,3]
|
<<
|
追加元素,但不排除重複元素
|
[1,2]<<[2,3] » [1,2,2,3]
|
|
|
追加元素,但排除重複元素
|
1,2] | [2,3] » [1,2,3]
|
-
|
返回第一個數組與第二個數組不同的元素
|
[1,2]-[2,3] » [1]
|
<=>
|
比較數組
|
[1,2]<=>[2,3] »flase
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==
|
比較數組,若所有元素均相等時返回真
|
[1,2]==[2,1] »flase
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assoc
|
從數組的每個元素中尋找指定對象
|
[[1,2],[3,4]].assoc(2) » [1,2]
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at
|
找到數組的第N個元素
負數表示逆向查找
|
["a","b","c","d","e"].at(0) » "a"
["a","b","c","d","e"].at(-1) » "e"
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clear
|
刪除數組中的所有元素
|
["a","b","c","d","e"]. clear
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collect
collect!
|
用一個過程塊對數組的每個元素進行處理
|
["a","b","c","d"].collect {|x| x + "!" }
» ["a!", "b!", "c!", "d!"]
|
compact
compact!
|
刪除值爲nil的元素後生成新數組並返回它
|
["a",nil,"b",nil,"c",nil].compact
» ["a", "b", "c"]
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delete
|
刪除元素,如果元素重複,全部刪除
|
a = [ "a", "b", "b", "b", "c" ]
a.delete("b")
puts a » ["a","c"]
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delete_at
|
刪除pos所指位置的元素並返回它。若pos超出數組範圍則返回nil
|
a = %w( ant bat cat dog )
a.delete_at(2) » "cat"
a » ["ant", "bat", "dog"]
a.delete_at(99) » nil
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delete_if
|
根據條件刪除
|
a = [ "a", "b", "c" ]
a.delete_if {|x| x >= "b" } » ["a"]
|
each
|
對數組的每個元素按值進行迭代操作
|
a = [ "a", "b", "c" ]
a.each {|x| print x, " -- " }
» "a -- b -- c --"
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each_index
|
對數組的每個元素按索引進行迭代操作
|
a = [ "a", "b", "c" ]
a.each_index {|x| print x, " -- " }
» "0 -- 1 -- 2 --"
|
empty?
|
判斷數組是否爲空,爲空則返回真
|
[].empty? » true
|
eql!
|
比較兩數組是否相等
|
["a","b","c"].eql?(["a","b","c"]) » true
|
fill
|
填充數組
|
["a","b","c","d"].fill("x")
» ["x","x","x","x"]
["a","b","c","d"].fill("z", 2, 2)
» ["x", "x", "z", "z"]
|
first
|
返回數組的首元素。若沒有首元素則返回nil
|
[ "q", "r", "s", "t" ].first » "q"
|
last
|
返回數組末尾的元素。若數組爲空時,返回nil
|
["w","x","y","z"].last » "z"
|
include?
|
判斷數組中是否包含元素
|
a = [ "a", "b", "c" ]
a.include?("b") » true
a.include?("z") » false
|
index
|
返回數組中第一個==val的元素的位置
|
a = [ "a", "b", "c" ]
a.index("b") » 1
a.index("z") » nil
|
indexes
|
以數組形式返回其索引值與各參數值相等的元素
|
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
|
在索引爲nth的元素前面插入第2參數以後的值
|
ary = %w(foo bar baz)
ary.insert 2,'a','b'
p ary » ["foo", "bar", "a", "b", "baz"]
|
join
|
將數組元素按一定的分隔符連接起來
|
[ "a", "b", "c" ].join » "abc"
[ "a", "b", "c" ].join("-") » "a-b-c"
|
length
size
|
返回數組長度。若數組爲空則返回0
|
[1,2,3].length » 3
[1,2,3].size » 3
|
nitems
|
返回非nil元素的個數
|
[ 1, nil, 3, nil, 5 ].nitems » 3
|
pop
|
刪除末尾元素並返回它。若數組爲空則返回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
|
遍歷數組每個元素(元素必須是數組),匹配索引爲1的值是否與查找的字符相等,返回第一個相等的元素
|
a = [[15,1], [25,2], [35,2]]
p a.rassoc(2) » [25, 2]
|
replace
|
替換數組元素
|
a = ["a","b"]
a.replace(["x","y","z"])
p a »["x", "y", "z"]
|
reverse
reverse!
|
將所有元素以逆序重新排列生成新數組並返回它
|
["a","b","c" ].reverse » ["c", "b", "a"]
|
rindex
|
返回最後一個值相等的元素的索引值
|
a = [ "a","b","b","b","c"]
a.rindex("b") » 3
|
shift
|
刪除數組的首元素並返回它。剩餘元素依次提前。若數組爲空返回nil。
|
args = ["-m","-q","filename"]
args.shift » "-m"
args » ["-q", "filename"]
|
sort
sort!
|
從小到大排序
|
a = [ "d", "a", "e", "c", "b" ]
a.sort » ["a", "b", "c", "d", "e"]
|
uniq
uniq!
|
刪除數組中的重複元素後生成新數組並返回它
|
a = [ "a", "a", "b", "b", "c" ]
a.uniq » ["a", "b", "c"]
|
unshift
|
在數組第一個元素前添加元素
|
a = [ "b", "c", "d" ]
a.unshift("a") » ["a", "b", "c", "d"]
|
to_s
|
將數組的所有元素連接成字符串
|
["a","e","i","o"].to_s » "aeio"
|
Ruby語言學習系列--Numeric類函數
函數名稱
|
說明
|
示例
|
chr
|
返回數字的ACSII碼
|
65.chr >> “A”
|
downto
|
接收一個block,從大到小循環執行
|
5.downto(2) { |i| puts i}
>> 5 4 3 2
|
upto
|
接收一個block,從小到大循環執行
|
2.upto(5) { |i| puts i}
>> 2 3 4 5
|
next或succ
|
返回下一個數
|
1.next >> 2
1.succ >>2
|
step
|
以固定步長循環執行
|
1.step(10,2) { |i| puts i}
>> 1 2 3 5 7
|
times
|
循環執行n次
|
5.times { |i| puts i}
>> 1 2 3 4 5
|
Ruby語言學習系列--Float類函數
函數名稱
|
說明
|
示例
|
ceil
|
返回比float大的最小整數
|
(2.98).ceil >> 3
|
floor
|
返回比float小的最大整數
|
(2.98). floor >> 2
|
round
|
四捨五入到一個整數
|
(2.98). round >> 3
|
to_i
|
返回float截掉小數點後的整數
|
(2.98).to_i >> 2
|
|