blocks|key|1264556|text|您可以使用Ruby的开放类来使代码更具可读性。例如，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1264557|class+String
++def+initial
++++self[0,1]
++end
end|code-block|syntax|javascript|1264558|将允许您对任何字符串使用initial方法。因此，如果您有以下变量：|offset|length|style|CODE|1264559|last_name+=+"Smith"
first_name+=+"John"|1264560|然后你就可以非常清晰和清晰地得到缩写了：|1264561|puts+first_name.initial+++#+prints+J
puts+last_name.initial++++#+prints+S|1264562|这里提到的另一种方法在Ruby+1.8上不起作用(并不是说你应该再用1.8了！--但是当这个答案发布时，它仍然很常见)：|1264563|puts+'Smith'[0]+++++++++++#+prints+83|1264564|当然，如果你不是经常这样做，那么定义方法可能有些夸张，你可以直接这样做：|1264565|puts+last_name[0,1]+|1264566|entityMap^0|0|0|C|7|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@$I|15|J|16|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1A|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|W|3|X|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|10|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|11|$]]

You can use Ruby's open classes to make your code much more readable. For instance, this:

<pre><code>class String
 def initial
 self[0,1]
 end
end
</code></pre>

will allow you to use the <code>initial</code> method on any string. So if you have the following variables:

<pre><code>last_name = "Smith"
first_name = "John"
</code></pre>

Then you can get the initials very cleanly and readably:

<pre><code>puts first_name.initial # prints J
puts last_name.initial # prints S
</code></pre>

The other method mentioned here doesn't work on Ruby 1.8 (not that you should be using 1.8 anymore anyway!--but when this answer was posted it was still quite common):

<pre><code>puts 'Smith'[0] # prints 83
</code></pre>

Of course, if you're not doing it on a regular basis, then defining the method might be overkill, and you could just do it directly:

<pre><code>puts last_name[0,1] 
</code></pre>

blocks|key|1264636|text|"Smith"[0..0]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1264637|适用于ruby+1.8和ruby+1.9。|unstyled|1264638|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>"Smith"[0..0]
</code></pre>

works in both ruby 1.8 and ruby 1.9.

blocks|key|1264734|text|为了完整起见，从Ruby1.9开始，String#chr返回字符串的第一个字符。它在2.0和2.1中仍然可用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1264735|"Smith".chr++++#=>+"S"|code-block|syntax|javascript|1264736|http://ruby-doc.org/core-1.9.3/String.html#method-i-chr|offset|length|1264737|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1J|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|T|8|@]|9|@$I|U|J|V|1|W]]|A|$]]|$1|K|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|H]]]]

For completeness sake, since Ruby 1.9 String#chr returns the first character of a string. Its still available in 2.0 and 2.1.

<pre><code>"Smith".chr #=&gt; "S"
</code></pre>

<a href="http://ruby-doc.org/core-1.9.3/String.html#method-i-chr" rel="noreferrer">http://ruby-doc.org/core-1.9.3/String.html#method-i-chr</a>

blocks|key|1049951|text|在MRI+1.8.7或更高版本中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1049952|'foobarbaz'.each_char.first|code-block|syntax|javascript|1049953|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In MRI 1.8.7 or greater:

<pre><code>'foobarbaz'.each_char.first
</code></pre>

blocks|key|1050051|text|在Rails中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1050052|name+=+'Smith'
name.first+|code-block|syntax|javascript|1050053|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In Rails

<pre><code>name = 'Smith'
name.first 
</code></pre>

blocks|key|1049782|text|>>+s+=+'Smith'++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
=>+"Smith"++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>+s[0]+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
=>+"S"++++++++++++++++++++++++++++++++++++++++++++++++++++++++|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1049783|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&gt;&gt; s = 'Smith' 
=&gt; "Smith" 
&gt;&gt; s[0] 
=&gt; "S" 
</code></pre>

blocks|key|1264849|text|另一个还没有被提及的选择：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1264850|>+"Smith".slice(0)
#=>+"S"|code-block|syntax|javascript|1264851|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Another option that hasn't been mentioned yet:

<pre><code>&gt; "Smith".slice(0)
#=&gt; "S"
</code></pre>

blocks|key|1050214|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1050215|def+word(string,+num)
++++string+=+'Smith'
++++string[0..(num-1)]
end|code-block|syntax|javascript|1050216|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:
<pre><code>def word(string, num)
 string = 'Smith'
 string[0..(num-1)]
end
</code></pre>

blocks|key|1050231|text|另一种方法是对字符串使用chars：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1050232|def+abbrev_name
++++first_name.chars.first.capitalize+%2B+'.'+%2B+'+'+%2B+last_name
end|code-block|syntax|javascript|1050233|entityMap|0|LINK|mutability|MUTABLE|url|https://ruby-doc.org/core/String.html#method-i-chars^0|C|5|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Other way around would be using the <a href="https://ruby-doc.org/core/String.html#method-i-chars" rel="nofollow noreferrer">chars</a> for a string:
<pre class="lang-rb prettyprint-override"><code>def abbrev_name
 first_name.chars.first.capitalize + '.' + ' ' + last_name
end
</code></pre>

blocks|key|1050191|text|如果你使用的是Rails，你也可以使用truncate|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1050192|>+'Smith'.truncate(1,+omission:+'')
#=>+"S"|code-block|syntax|javascript|1050193|或用于其他格式：|1050194|>+'Smith'.truncate(4)
#=>+"S..."

>+'Smith'.truncate(2,+omission:+'.')
#=>+"S."|1050195|虽然对于原始问题来说，这绝对是夸大其词，但对于纯ruby解决方案，下面是truncate是如何在rails中实现的|1050196|#+File+activesupport/lib/active_support/core_ext/string/filters.rb,+line+66
def+truncate(truncate_at,+options+=+{})
++return+dup+unless+length+>+truncate_at

++omission+=+options[:omission]+%7C%7C+"..."
++length_with_room_for_omission+=+truncate_at+-+omission.length
++stop+=++++++++if+options[:separator]
++++++rindex(options[:separator],+length_with_room_for_omission)+%7C%7C+length_with_room_for_omission
++++else
++++++length_with_room_for_omission
++++end

++"#{self[0,+stop]}#{omission}"
end|1050197|entityMap|0|LINK|mutability|MUTABLE|url|https://apidock.com/rails/String/truncate^0|7|5|J|8|J|8|0|0|0|0|0|O|4|10|8|1C|5|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]]|E|$]]|$1|F|3|G|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|19|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1I|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

If you're using <code>Rails</code> You can also use <a href="https://apidock.com/rails/String/truncate" rel="nofollow noreferrer"><code>truncate</code></a>
<pre><code>&gt; 'Smith'.truncate(1, omission: '')
#=&gt; &quot;S&quot;
</code></pre>
or for additional formatting:
<pre><code>&gt; 'Smith'.truncate(4)
#=&gt; &quot;S...&quot;

&gt; 'Smith'.truncate(2, omission: '.')
#=&gt; &quot;S.&quot;
</code></pre>
While this is definitely overkill for the original question, for a pure <code>ruby</code> solution, here is how <code>truncate</code> is implemented in <code>rails</code>
<pre><code># File activesupport/lib/active_support/core_ext/string/filters.rb, line 66
def truncate(truncate_at, options = {})
 return dup unless length &gt; truncate_at

 omission = options[:omission] || &quot;...&quot;
 length_with_room_for_omission = truncate_at - omission.length
 stop = if options[:separator]
 rindex(options[:separator], length_with_room_for_omission) || length_with_room_for_omission
 else
 length_with_room_for_omission
 end

 &quot;#{self[0, stop]}#{omission}&quot;
end
</code></pre>

blocks|key|1264810|text|这些方法中的任何一种都可以：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1264811|name+=+'Smith'
puts+name.[0..0]+#+=>+S
puts+name.[0]+#+=>+S
puts+name.[0,1]+#+=>+S
puts+name.[0].chr+#+=>+S|code-block|syntax|javascript|1264812|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Any of these methods will work:

<pre><code>name = 'Smith'
puts name.[0..0] # =&gt; S
puts name.[0] # =&gt; S
puts name.[0,1] # =&gt; S
puts name.[0].chr # =&gt; S
</code></pre>

How can I get the first character in a string using Ruby?

Ultimately what I'm doing is taking someone's last name and just creating an initial out of it.

So if the string was "Smith" I just want "S".

Ruby: How to get the first character of a string

如何使用Ruby获取字符串中的第一个字符？最终，我要做的就是取一个人的姓氏，然后用它来创建一个首字母。所以如果字符串是"Smith“，我只想要"S”。

问Ruby:如何获取字符串的第一个字符
EN

回答 11

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问Ruby:如何获取字符串的第一个字符
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