blocks|key|1668599|text|为什么不在sub!方法中包含正则表达式呢？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1668600|string.sub!(/%5E1/,+'')|code-block|syntax|javascript|1668601|entityMap^0|5|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Why not just include the regex in the <code>sub!</code> method?

<pre><code>string.sub!(/^1/, '')
</code></pre>

blocks|key|1453684|text|如果您打算使用正则表达式进行匹配，那么您也可以将其用于替换|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1453685|string.sub!(%25r{%5E1},"")|code-block|syntax|javascript|1453686|顺便说一句，%25r{}只是正则表达式的替代语法。您可以使用%25r后跟任何字符，例如%25r!%5E1!。|offset|length|style|CODE|1453687|entityMap^0|0|0|6|4|13|6|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

if you're going to use regex for the match, you may as well use it for the replacement

<pre><code>string.sub!(%r{^1},"")
</code></pre>

BTW, the <code>%r{}</code> is just an alternate syntax for regular expressions. You can use %r followed by any character e.g. <code>%r!^1!</code>.

blocks|key|1668751|text|小心使用sub!(/%5E1/,'')！如果字符串与/%5E1/不匹配，它将返回nil。您可能应该使用sub+(不带bang)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1668752|entityMap^0|4|D|O|4|10|3|1B|3|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

Careful using <code>sub!(/^1/,'')</code> ! In case the string doesn't match <code>/^1/</code> it will return <code>nil</code>. You should probably use <code>sub</code> (without the bang).

blocks|key|1453795|text|这个答案可能会更优化：What+is+the+easiest+way+to+remove+the+first+character+from+a+string?|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1453796|string[0]+=+''+if+string[0]+==+'1'|style|CODE|1453797|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/3614389/what-is-the-easiest-way-to-remove-the-first-character-from-a-string^0|B|1W|0|0|0|Y|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@$A|U|B|V|F|G]]|9|@]|C|$]]|$1|H|3|-4|5|6|7|W|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

This answer might be more optimised: <a href="https://stackoverflow.com/questions/3614389/what-is-the-easiest-way-to-remove-the-first-character-from-a-string">What is the easiest way to remove the first character from a string?</a>

<code>string[0] = '' if string[0] == '1'</code>

blocks|key|1668861|text|从Ruby2.5开始，你可以使用delete_prefix或delete_prefix！以一种可读的方式实现这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1668862|在本例中为"1hello+world".delete_prefix("1")。|style|CODE|1668863|更多信息请点击此处：|1668864|https://blog.jetbrains.com/ruby/2017/10/10-new-features-in-ruby-2-5/|1668865|https://bugs.ruby-lang.org/issues/12694|1668866|'invisible'.delete_prefix('in')+#=>+"visible"
'pink'.delete_prefix('in')+#=>+"pink"|code-block|syntax|javascript|1668867|注意:你也可以用delete_suffix和delete_suffix来删除字符串末尾的项目。|1668868|'worked'.delete_suffix('ed')+#=>+"work"
'medical'.delete_suffix('ed')+#=>+"medical"|1668869|https://bugs.ruby-lang.org/issues/13665|1668870|我在这里更详细地回答了(使用基准测试)：What+is+the+easiest+way+to+remove+the+first+character+from+a+string?|1668871|entityMap|0|LINK|mutability|MUTABLE|url|https://ruby-doc.org/core-2.5.1/String.html#method-i-delete_prefix|1|2|3|4|https://stackoverflow.com/questions/3614389/what-is-the-easiest-way-to-remove-the-first-character-from-a-string#answer-46958806^0|G|D|0|0|5|X|0|0|0|1W|1|0|0|13|2|0|0|0|0|0|13|3|0|K|1W|4|0^^$0|@$1|2|3|4|5|6|7|1D|8|@]|9|@$A|1E|B|1F|1|1G]]|C|$]]|$1|D|3|E|5|6|7|1H|8|@$A|1I|B|1J|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|1K|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|1L|8|@]|9|@$A|1M|B|1N|1|1O]]|C|$]]|$1|L|3|M|5|6|7|1P|8|@]|9|@$A|1Q|B|1R|1|1S]]|C|$]]|$1|N|3|O|5|P|7|1T|8|@]|9|@]|C|$Q|R]]|$1|S|3|T|5|6|7|1U|8|@]|9|@]|C|$]]|$1|U|3|V|5|P|7|1V|8|@]|9|@]|C|$Q|R]]|$1|W|3|X|5|6|7|1W|8|@]|9|@$A|1X|B|1Y|1|1Z]]|C|$]]|$1|Y|3|Z|5|6|7|20|8|@]|9|@$A|21|B|22|1|23]]|C|$]]|$1|10|3|-4|5|6|7|24|8|@]|9|@]|C|$]]]|11|$12|$5|13|14|15|C|$16|17]]|18|$5|13|14|15|C|$16|K]]|19|$5|13|14|15|C|$16|M]]|1A|$5|13|14|15|C|$16|X]]|1B|$5|13|14|15|C|$16|1C]]]]

As of Ruby 2.5 you can use <a href="https://ruby-doc.org/core-2.5.1/String.html#method-i-delete_prefix" rel="noreferrer">delete_prefix</a> or delete_prefix! to achieve this in a readable manner.

In this case <code>"1hello world".delete_prefix("1")</code>.

More info here:

<a href="https://blog.jetbrains.com/ruby/2017/10/10-new-features-in-ruby-2-5/" rel="noreferrer">https://blog.jetbrains.com/ruby/2017/10/10-new-features-in-ruby-2-5/</a>

<a href="https://bugs.ruby-lang.org/issues/12694" rel="noreferrer">https://bugs.ruby-lang.org/issues/12694</a>

<pre><code>'invisible'.delete_prefix('in') #=&gt; "visible"
'pink'.delete_prefix('in') #=&gt; "pink"
</code></pre>

N.B. you can also use this to remove items from the end of a string with delete_suffix and delete_suffix!

<pre><code>'worked'.delete_suffix('ed') #=&gt; "work"
'medical'.delete_suffix('ed') #=&gt; "medical"
</code></pre>

<a href="https://bugs.ruby-lang.org/issues/13665" rel="noreferrer">https://bugs.ruby-lang.org/issues/13665</a>

I've answered in a little more detail (with benchmarks) here: <a href="https://stackoverflow.com/questions/3614389/what-is-the-easiest-way-to-remove-the-first-character-from-a-string#answer-46958806">What is the easiest way to remove the first character from a string?</a>

How can I remove the very first "1" from any string if that string starts with a "1"?

<pre><code>"1hello world" =&gt; "hello world"
"112345" =&gt; "12345"
</code></pre>

I'm thinking of doing

<pre><code>string.sub!('1', '') if string =~ /^1/
</code></pre>

but I' wondering there's a better way. Thanks!

Remove character from string if it starts with that character?

如果字符串以"1“开头，我如何从该字符串中删除第一个"1"？"1hello world" => "hello world""112345" => "12345"我在考虑做什么string.sub!('1', '') if string =~ /^1/但我在想有没有更好的方法。谢谢!

问如果字符串以该字符开头，是否删除该字符？
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问如果字符串以该字符开头，是否删除该字符？
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