我怎么能检查字符串中是否存在单词，如果不存在则返回false，在ruby中？

Say I have a string str = "Things to do: eat and sleep."

说我有一个字符串str =“要做的事情：吃饭和睡觉。”

How could I check if "do: " exists in str, case insensitive?

我如何检查str中是否存在“do：”，不区分大小写？

5 个解决方案

#1

Like this:

喜欢这个：

puts "yes" if str =~ /do:/i

To return a boolean value (from a method, presumably), compare the result of the match to nil:

要返回一个布尔值（可能来自一个方法），请将匹配结果与nil进行比较：

def has_do(str)
    (str =~ /do:/i) != nil
end

Or, if you don’t like the != nil then you can use !~ instead of =~ and negate the result:

或者，如果你不喜欢！= nil那么你可以使用！〜而不是=〜并否定结果：

def has_do(str)
    not str !~ /do:/i
end

But I don’t really like double negations …

但我真的不喜欢双重否定......

#2

In ruby 1.9 you can do like this:

在ruby 1.9中你可以这样做：

str.downcase.match("do: ") do   
  puts "yes" 
end

It's not exactly what you asked for, but I noticed a comment to another answer. If you don't mind using regular expressions when matching the string, perhaps there is a way to skip the downcase part to get case insensitivity.

这不完全是你要求的，但我注意到对另一个答案的评论。如果你不介意在匹配字符串时使用正则表达式，也许有一种方法可以跳过downcase部分以获得不区分大小写。

For more info, see String#match

有关更多信息，请参阅String #matre

#3

You could also do this:

你也可以这样做：

str.downcase.include? "Some string".downcase

#4

If all I'm looking for is a case=insensitive substring match I usually use:

如果我正在寻找的是一个case = insensitive substring match我通常使用：

str.downcase['do: ']

9 times out of 10 I don't care where in the string the match is, so this is nice and concise.

10次中有9次我不在乎比赛中的字符串在哪里，所以这很简洁。

Here's what it looks like in IRB:

这是IRB的样子：

>> str = "Things to do: eat and sleep." #=> "Things to do: eat and sleep."
>> str.downcase['do: '] #=> "do: "
>> str.downcase['foobar'] #=> nil

Because it returns nil if there is no hit it works in conditionals too.

因为如果没有命中它会返回nil，它也会在条件中起作用。

#5

"Things to do: eat and sleep.".index(/do: /i)

index returns the position where the match starts, or nil if not found

index返回匹配开始的位置，如果未找到则返回nil

You can learn more about index method here: http://ruby-doc.org/core/classes/String.html

您可以在此处了解有关索引方法的更多信息：http：//ruby-doc.org/core/classes/String.html

Or about regex here: http://www.regular-expressions.info/ruby.html

或者关于正则表达式：http：//www.regular-expressions.info/ruby.html

#1