blocks|key|1457533|text|字符串是不可变的，所以您不能在现有字符串中插入字符。你必须创建一个新的字符串。您可以使用字符串连接来执行您想要的操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1457534|yourstring+=+"L"+%2B+yourstring+%2B+"LL"|code-block|syntax|javascript|1457535|请注意，您还可以使用乘法创建具有n个L的字符串：|offset|length|style|CODE|1457536|m+=+1
n+=+2
yourstring+=+("L"+*+m)+%2B+yourstring+%2B+("L"+*+n)|1457537|entityMap^0|0|0|I|1|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Strings are immutable so you can't insert characters into an existing string. You have to create a new string. You can use string concatenation to do what you want:

<pre><code>yourstring = "L" + yourstring + "LL"
</code></pre>

Note that you can also create a string with n <code>L</code>s by using multiplication:

<pre><code>m = 1
n = 2
yourstring = ("L" * m) + yourstring + ("L" * n)
</code></pre>

blocks|key|5196999|text|对于完备性和其他答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5197000|yourstring+=+"L%25sLL"+%25+yourstring|code-block|syntax|javascript|5197001|或者，更向前兼容Python+3.x：|5197002|yourstring+=+"L{0}LL".format(yourstring)|5197003|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For completeness along with the other answers:

<pre><code>yourstring = "L%sLL" % yourstring
</code></pre>

Or, more forward compatible with Python 3.x:

<pre><code>yourstring = "L{0}LL".format(yourstring)
</code></pre>

blocks|key|1453153|text|您还可以使用join：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1453154|yourstring+=+''.join(('L','yourstring','LL'))|code-block|syntax|javascript|1453155|结果：|1453156|>>>+yourstring
'LyourstringLL'|1453157|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can also use join:

<pre><code>yourstring = ''.join(('L','yourstring','LL'))
</code></pre>

Result:

<pre><code>&gt;&gt;&gt; yourstring
'LyourstringLL'
</code></pre>

blocks|key|1668194|text|如果要在现有字符串中其他位置插入其他字符串，可以使用下面的选择方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1668195|在第二个位置调用字符：|1668196|>>>+s+=+"0123456789"
>>>+s[2]
'2'|code-block|syntax|javascript|1668197|起始位置和结束位置的调用范围：|1668198|>>>+s[4:6]
'45'|1668199|在该位置之前调用字符串的一部分：|1668200|>>>+s[:6]
'012345'|1668201|在该位置之后调用字符串的一部分：|1668202|>>>+s[4:]
'456789'|1668203|将你的字符串插入到第五个位置。|1668204|>>>+s+=+s[:5]+%2B+"L"+%2B+s[5:]
>>>+s
'01234L56789'|1668205|此外，s等同于s[:]。|offset|length|style|CODE|1668206|对于你的问题，你可以使用你所有的字符串，即|1668207|>>>+s+=+"L"+%2B+s+%2B+"LL"|1668208|或者，如果"L"是另一个字符串(例如，我将其称为l)，则可以使用该代码：|1668209|>>>+s+=+l+%2B+s+%2B+(l+*+2)|1668210|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|3|1|7|4|0|0|0|5|3|O|1|0|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1G|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|1H|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|1I|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|1J|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|1K|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|1L|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|1M|8|@]|9|@]|A|$G|H]]|$1|U|3|V|5|6|7|1N|8|@]|9|@]|A|$]]|$1|W|3|X|5|F|7|1O|8|@]|9|@]|A|$G|H]]|$1|Y|3|Z|5|6|7|1P|8|@$10|1Q|11|1R|12|13]|$10|1S|11|1T|12|13]]|9|@]|A|$]]|$1|14|3|15|5|6|7|1U|8|@]|9|@]|A|$]]|$1|16|3|17|5|F|7|1V|8|@]|9|@]|A|$G|H]]|$1|18|3|19|5|6|7|1W|8|@$10|1X|11|1Y|12|13]|$10|1Z|11|20|12|13]]|9|@]|A|$]]|$1|1A|3|1B|5|F|7|21|8|@]|9|@]|A|$G|H]]|$1|1C|3|-4|5|6|7|22|8|@]|9|@]|A|$]]]|1D|$]]

If you want to insert other string somewhere else in existing string, you may use selection method below.

Calling character on second position:

<pre><code>&gt;&gt;&gt; s = "0123456789"
&gt;&gt;&gt; s[2]
'2'
</code></pre>

Calling range with start and end position:

<pre><code>&gt;&gt;&gt; s[4:6]
'45'
</code></pre>

Calling part of a string before that position:

<pre><code>&gt;&gt;&gt; s[:6]
'012345'
</code></pre>

Calling part of a string after that position:

<pre><code>&gt;&gt;&gt; s[4:]
'456789'
</code></pre>

Inserting your string in 5th position.

<pre><code>&gt;&gt;&gt; s = s[:5] + "L" + s[5:]
&gt;&gt;&gt; s
'01234L56789'
</code></pre>

Also <code>s</code> is equivalent to <code>s[:]</code>.

With your question you can use all your string, i.e.

<pre><code>&gt;&gt;&gt; s = "L" + s + "LL"
</code></pre>

or if <code>"L"</code> is a some other string (for example I call it as <code>l</code>), then you may use that code:

<pre><code>&gt;&gt;&gt; s = l + s + (l * 2)
</code></pre>

blocks|key|1453199|text|在Python+3.6%2B中，添加到C2H5OH's+answer中，您可以使用格式字符串使其更简洁：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1453200|s+=+"something+about+cupcakes"
print(f"L{s}LL")|code-block|syntax|javascript|1453201|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/10059623/943773^0|H|F|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]]]]

Adding to <a href="https://stackoverflow.com/a/10059623/943773">C2H5OH's answer</a>, in Python 3.6+ you can use format strings to make it a bit cleaner:

<pre><code>s = "something about cupcakes"
print(f"L{s}LL")
</code></pre>

blocks|key|1457559|text|假设我们有一个名为have+string的字符串：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1457560|for+x+in+range(0,+[howmanytimes+you+want+it+at+the+beginning]):
++++yourstring+=+"L"+%2B+yourstring
for+x+in+range(0,+[howmanytimes+you+want+it+at+the+end]):
++++yourstring+%2B=+"L"|code-block|syntax|javascript|1457561|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|$]]

Let's say we have a string called yourstring:

<pre><code>for x in range(0, [howmanytimes you want it at the beginning]):
 yourstring = "L" + yourstring
for x in range(0, [howmanytimes you want it at the end]):
 yourstring += "L"
</code></pre>

blocks|key|5197104|text|为此，您可以使用f字符串|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5197105|foo+=+"where+did+I+put+my+cupcake+this+morning"
bar+=+'L'
foobar+=+f'{bar*10}{foo}'
print(foobar)|code-block|syntax|javascript|5197106|您可以将10替换为您希望在字符串中为end添加L的次数，也可以执行相同的操作|offset|length|style|CODE|5197107|foo+=+"where+did+I+put+my+cupcake+this+morning"
bar+=+'L'
foobar+=+f'{bar*10}{foo}{bar*10}'
print(foobar)|5197108|entityMap^0|0|0|4|2|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

you can use f strings for this
<pre class="lang-py prettyprint-override"><code>foo = &quot;where did I put my cupcake this morning&quot;
bar = 'L'
foobar = f'{bar*10}{foo}'
print(foobar)
</code></pre>
you can replace <code>10</code> by how many times you want to put L's in your string
for end also you can do the same
<pre class="lang-py prettyprint-override"><code>foo = &quot;where did I put my cupcake this morning&quot;
bar = 'L'
foobar = f'{bar*10}{foo}{bar*10}'
print(foobar)
</code></pre>

I am new and trying to find a way to insert a number of L's at the beginning and end of a string. So if I have a string which says 

"where did I put my cupcake this morning" 

And I want to insert 1 L at the start and 2 L's at the end, so it looks like: "Lwhere did I put my cupcake this morningLL" How do I do this. thank you

inserting characters at the start and end of a string

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我是个新手，正在尝试找到一种方法来在字符串的开头和结尾插入一些L。所以如果我有一个字符串，它说“今天早上我把纸杯蛋糕放哪了？”我想在开头插入1个L，在末尾插入2个L，这样看起来就像：“我把我的纸杯蛋糕放在哪里了，这个morningLL”，我该怎么做？谢谢

问在字符串的开头和结尾插入字符
EN

回答 7

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问在字符串的开头和结尾插入字符
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