1,使用疊代器和join的不同
- data=['1','2','3']
- s=''
- data.each{|x| s<<x<<' and '}
- puts s
- puts data.join(" and ")
line 4輸出的是:1 and 2 and 3 and
line 5則是:1 and 2 and 3
可以使用each_with_index實作join
data.each_with_index{|x,i| ss<<x;ss<<' and ' if i<data.length-1}
2,<< pk +
使用前者向string中append時會比後者的性能有所提高,因為後者會建立新的string對象。
3,You want to create a string that contains a representation of a Ruby
variable or expression.
eg: number=5
puts "the number is #{number}"
puts "the number is #{5}"
puts "the number now is #{number-1}"
puts "the number is #{number.next} or #{number.prior}"
沒有Fixnum#prior方法。
Discussion
1)#{}中定義的變量或者類可以在#{}之外使用
puts "Here is #{
class Bar
def bar
" some text"
end
end
Bar.new.bar}"
bar=Bar.new
puts bar.bar
輸出:Here is some text
some text
2)避免#{}的轉義作用
foo="foo"
puts "\##{foo}"
puts '#{foo}'
puts '\#{foo}'
puts "#{foo}"
puts "\#"
3)使用END
name = "Mr. Lorum"
email = <<END
Dear #{name},
Unfortunately we cannot process your insurance claim at this
time. This is because we are a bakery, not an insurance company.
Signed,Nil, Null, and None
Bakers to Her Majesty the Singleton
END
puts email
另外END可以用任意的字元替代。
hello=<<ok
Does it ok?
ok
puts hello
這裡有一個問題就是END前面不能有空格?