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假设我有一组 Twitter 帐户名称：

string = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]

还有一个前置和附加变量：

prepend = 'Check out these cool people: '
append = ' #FollowFriday'

如何将其转换为尽可能少的字符串数组，每个字符串的最大长度为 140 个字符，从前置文本开始，以附加文本结尾，在 Twitter 帐户名称之间都以 @-sign 和用空格隔开。像这样：

tweets = ['Check out these cool people: @example1 @example2 @example3 @example4 @example5 @example6 @example7 @example8 @example9 #FollowFriday', 'Check out these cool people: @example10 @example11 @example12 @example13 @example14 @example15 @example16 @example17 #FollowFriday', 'Check out these cool people: @example18 @example19 @example20 #FollowFriday']

（帐户的顺序并不重要，因此理论上您可以尝试找到最佳顺序以充分利用可用空间，但这不是必需的。）

有什么建议么？我想我应该使用该scan方法，但还没有找到正确的方法。

使用一堆循环很容易，但我猜在使用正确的 Ruby 方法时这不是必需的。到目前为止，这是我想出的：

# Create one long string of @usernames separated by a space
tmp = twitter_accounts.map!{|a| a.insert(0, '@')}.join(' ')
# alternative: tmp = '@' + twitter_accounts.join(' @')

# Number of characters left for mentioning the Twitter accounts
length = 140 - (prepend + append).length

# This method would split a string into multiple strings
# each with a maximum length of 'length' and it will only split on empty spaces (' ')
# ideally strip that space as well (although .map(&:strip) could be use too) 
tweets = tmp.some_method(' ', length)

# Prepend and append
tweets.map!{|t| prepend + t + append}

PS如果有人对更好的标题有建议，请告诉我。我很难总结我的问题。

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2 回答 2

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Stringrindex方法有一个可选参数，您可以在其中指定从何处开始在字符串中向后搜索：

arr = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]
str = arr.map{|name|"@#{name}"}.join(' ')
prepend =  'Check out these cool people: '
append = ' #FollowFriday'
max_chars = 140 - prepend.size - append.size
until str.size <= max_chars do
  p str.slice!(0, str.rindex(" ", max_chars))
  str.lstrip! #get rid of the leading space
end
p str unless str.empty?
于 2013-04-19T22:41:04.053 回答
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我会利用reduce这个：

string = %w[example1 example2 example3 example4 example5 example6 example7 example8 example9 example10 example11 example12 example13 example14 example15 example16 example17 example18 example19 example20]
prepend = 'Check out these cool people:'
append = '#FollowFriday'

# Extra -1 is for the space before `append`
max_content_length = 140 - prepend.length - append.length - 1

content_strings = string.reduce([""]) { |result, target|
  result.push("") if result[-1].length + target.length + 2 > max_content_length
  result[-1] += " @#{target}"

  result
}

tweets = content_strings.map { |s| "#{prepend}#{s} #{append}" }

这将产生：

"Check out these cool people: @example1 @example2 @example3 @example4 @example5 @example6 @example7 @example8 @example9 #FollowFriday"
"Check out these cool people: @example10 @example11 @example12 @example13 @example14 @example15 @example16 @example17 #FollowFriday"
"Check out these cool people: @example18 @example19 @example20 #FollowFriday"
于 2013-04-19T21:56:40.117 回答