im from php,
in php i overly 开发者_运维知识库use .=
so, how do it in ruby?
String concatentation is done with +
in Ruby:
$ irb
irb(main):001:0> "hello" + " " + "world"
=> "hello world"
irb(main):002:0> foo = "hello "
=> "hello "
irb(main):003:0> foo += "world"
=> "hello world"
@AboutRuby also mentions the <<
operator:
irb(main):001:0> s = "hello"
=> "hello"
irb(main):002:0> s << " world"
=> "hello world"
irb(main):003:0> s
=> "hello world"
While his point that +
creates a new string and <<
modifies a string might seem like a small point, it matters a lot when you might have multiple references to your string object, or if your strings grow to be huge via repeated appending:
irb(main):004:0> my_list = [s, s]
=> ["hello world", "hello world"]
irb(main):005:0> s << "; goodbye, world"
=> "hello world; goodbye, world"
irb(main):006:0> my_list
=> ["hello world; goodbye, world", "hello world; goodbye, world"]
irb(main):007:0> t = "hello, world"
=> "hello, world"
irb(main):008:0> my_list = [t, t]
=> ["hello, world", "hello, world"]
irb(main):009:0> t += "; goodbye, world"
=> "hello, world; goodbye, world"
irb(main):010:0> my_list
=> ["hello, world", "hello, world"]
@AboutRuby mentioned he could think of three mechanisms for string concatenation; that reminded me of another mechanism, which is more appropriate when you've got an array of strings that you wish to join together:
irb(main):015:0> books = ["war and peace", "crime and punishment", "brothers karamozov"]
=> ["war and peace", "crime and punishment", "brothers karamozov"]
irb(main):016:0> books.join("; ")
=> "war and peace; crime and punishment; brothers karamozov"
The .join()
method can save you from writing some awful loops. :)
Use +=
. or .concat("string to add")
Is that for string concatenation? You use +=
in ruby to concat string.
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