blocks|key|549851|text|使用tonumber+function。就像a+=+tonumber("10")一样。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|549852|entityMap|0|LINK|mutability|MUTABLE|url|http://www.lua.org/manual/5.1/manual.html#pdf-tonumber^0|2|8|M|I|2|H|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

Use the <a href="http://www.lua.org/manual/5.1/manual.html#pdf-tonumber" rel="noreferrer"><code>tonumber</code> function</a>. As in <code>a = tonumber("10")</code>.

blocks|key|549913|text|您可以像在a=+"10"+%2B+0中那样，通过在算术操作中使用字符串来强制执行隐式转换，但这并不像显式使用tonumber那样清晰或干净。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|549914|entityMap^0|5|B|1G|8|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

You can force an implicit conversion by using a string in an arithmetic operations as in <code>a= "10" + 0</code>, but this is not quite as clear or as clean as using <code>tonumber</code> explicitly.

blocks|key|333330|text|假设要转换为数字的字符串在变量S中|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|333331|a=tonumber(S)|code-block|syntax|javascript|333332|如果S中有数字且只有数字，它将返回一个数字，但如果有任何不是数字的字符(浮点数的句号除外)，它将返回nil|333333|entityMap^0|F|1|0|0|2|1|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

say the string you want to turn into a number is in the variable <code>S</code>

<pre><code>a=tonumber(S)
</code></pre>

provided that there are numbers and only numbers in <code>S</code> it will return a number,
but if there are any characters that are not numbers (except periods for floats)
it will return nil

blocks|key|550141|text|应该注意的是，math.floor()总是向下舍入，因此对于负的浮点值不会产生合理的结果。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|550142|例如，表示为整数的-10.4通常会被截断或舍入为-10。但是math.floor()的结果是不一样的：|550143|math.floor(-10.4)+=>+-11|code-block|syntax|javascript|550144|对于带有类型转换的截断，以下辅助函数将起作用：|550145|function+tointeger(+x+)
++++num+=+tonumber(+x+)
++++return+num+<+0+and+math.ceil(+num+)+or+math.floor(+num+)
end|550146|参考：http://lua.2524044.n2.nabble.com/5-3-Converting-a-floating-point-number-to-integer-td7664081.html|550147|entityMap|0|LINK|mutability|MUTABLE|url|http://lua.2524044.n2.nabble.com/5-3-Converting-a-floating-point-number-to-integer-td7664081.html^0|7|C|0|0|0|0|0|3|2P|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|13|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|15|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|S|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

It should be noted that <code>math.floor()</code> always rounds down, and therefore does not yield a sensible result for negative floating point values.

For example, -10.4 represented as an integer would usually be either truncated or rounded to -10. Yet the result of math.floor() is not the same:

<pre><code>math.floor(-10.4) =&gt; -11
</code></pre>

For truncation with type conversion, the following helper function will work:

<pre><code>function tointeger( x )
 num = tonumber( x )
 return num &lt; 0 and math.ceil( num ) or math.floor( num )
end
</code></pre>

Reference: <a href="http://lua.2524044.n2.nabble.com/5-3-Converting-a-floating-point-number-to-integer-td7664081.html" rel="nofollow noreferrer">http://lua.2524044.n2.nabble.com/5-3-Converting-a-floating-point-number-to-integer-td7664081.html</a>

blocks|key|550193|text|tonumber+(e+[,+base])|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|550194|tonumber有两个参数，第一个是字符串，它被转换成数字，第二个是e的基数。|550195|返回值tonumber以10为基数。|550196|如果没有提供base，它会将数字转换为基数10。|550197|>+a+=+'101'
>+tonumber(a)
101|code-block|syntax|javascript|550198|如果提供了base，它会将其转换为给定的base。|550199|>+a+=+'101'
>+
>+tonumber(a,+2)
5
>+tonumber(a,+8)
65
>+tonumber(a,+10)
101
>+tonumber(a,+16)
257
>+|550200|如果e包含无效字符，则返回nil。|550201|>+--[[+Failed+because+base+2+numbers+consist+(0+and+1)+--]]
>+a+=+'112'
>+tonumber(a,+2)
nil
>+
>+--[[+similar+to+above+one,+this+failed+because+--]]
>+--[[+base+8+consist+(0+-+7)+--]]
>+--[[+base+10+consist+(0+-+9)+--]]
>+a+=+'AB'
>+tonumber(a,+8)
nil
>+tonumber(a,+10)
nil
>+tonumber(a,+16)
171|550202|我回答时考虑到了Lua5.3|550203|entityMap|0|LINK|mutability|MUTABLE|url|https://www.lua.org/manual/5.3/manual.html#pdf-tonumber^0|0|L|0|L|0|0|0|8|Y|1|0|3|8|0|6|4|0|0|0|0|2|1|D|3|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@$9|19|A|1A|B|C]]|D|@$9|1B|A|1C|1|1D]]|E|$]]|$1|F|3|G|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1J|8|@$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|1M|8|@$9|1N|A|1O|B|C]]|D|@]|E|$]]|$1|L|3|M|5|N|7|1P|8|@]|D|@]|E|$O|P]]|$1|Q|3|R|5|6|7|1Q|8|@]|D|@]|E|$]]|$1|S|3|T|5|N|7|1R|8|@]|D|@]|E|$O|P]]|$1|U|3|V|5|6|7|1S|8|@$9|1T|A|1U|B|C]|$9|1V|A|1W|B|C]]|D|@]|E|$]]|$1|W|3|X|5|N|7|1X|8|@]|D|@]|E|$O|P]]|$1|Y|3|Z|5|6|7|1Y|8|@]|D|@]|E|$]]|$1|10|3|-4|5|6|7|1Z|8|@]|D|@]|E|$]]]|11|$12|$5|13|14|15|E|$16|17]]]]

<a href="https://www.lua.org/manual/5.3/manual.html#pdf-tonumber" rel="nofollow noreferrer"><code>tonumber (e [, base])</code></a>

<code>tonumber</code> takes two arguments, first is string which is converted to number and second is base of <code>e</code>.

Return value <code>tonumber</code> is in base 10.

If no <code>base</code> is provided it converts number to base 10.

<pre><code>&gt; a = '101'
&gt; tonumber(a)
101
</code></pre>

If base is provided, it converts it to the given base.

<pre><code>&gt; a = '101'
&gt; 
&gt; tonumber(a, 2)
5
&gt; tonumber(a, 8)
65
&gt; tonumber(a, 10)
101
&gt; tonumber(a, 16)
257
&gt; 
</code></pre>

If <code>e</code> contains invalid character then it returns <code>nil</code>.

<pre><code>&gt; --[[ Failed because base 2 numbers consist (0 and 1) --]]
&gt; a = '112'
&gt; tonumber(a, 2)
nil
&gt; 
&gt; --[[ similar to above one, this failed because --]]
&gt; --[[ base 8 consist (0 - 7) --]]
&gt; --[[ base 10 consist (0 - 9) --]]
&gt; a = 'AB'
&gt; tonumber(a, 8)
nil
&gt; tonumber(a, 10)
nil
&gt; tonumber(a, 16)
171
</code></pre>

I answered considering Lua5.3

blocks|key|550066|text|你可以创建一个存取器来保持"+10“为整数10。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|550067|示例：|550068|x+=+tonumber("10")|code-block|syntax|javascript|550069|如果打印x变量，它将输出一个int+10，而不是"10“|550070|与Python过程相同|550071|X=+int("10")|550072|谢谢。|550073|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

You can make an accessor to keep the "10" as int 10 in it.

Example:

<pre><code>x = tonumber("10")
</code></pre>

if you print the x variable, it will output an int 10 and not "10"

same like Python process

x = int("10")

Thanks.

blocks|key|333438|text|Lua+5.3.1++Copyright+(C)+1994-2015+Lua.org,+PUC-Rio
>+math.floor("10");
10
>+tonumber("10");
10
>+"10"+%2B+0;
10.0
>+"10"+%7C+0;
10|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|333439|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>Lua 5.3.1 Copyright (C) 1994-2015 Lua.org, PUC-Rio
&gt; math.floor("10");
10
&gt; tonumber("10");
10
&gt; "10" + 0;
10.0
&gt; "10" | 0;
10
</code></pre>

blocks|key|550283|text|从Lua5.3开始，有了一个新的math.tointeger函数，可以将字符串转换为整数。仅用于整型，无浮点型。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|550284|例如：|550285|print(math.tointeger("10.1"))+--+nil
print(math.tointeger("10"))+--+10|code-block|syntax|javascript|550286|如果您想转换整数和浮点数，tonumber函数更合适。|550287|entityMap^0|G|E|0|0|0|D|8|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

Since lua 5.3 there is a new <code>math.tointeger</code> function for string to integer. Just for integer, no float.
For example:
<pre class="lang-lua prettyprint-override"><code>print(math.tointeger(&quot;10.1&quot;)) -- nil
print(math.tointeger(&quot;10&quot;)) -- 10
</code></pre>
If you want to convert integer and float, the <code>tonumber</code> function is more appropriate.

blocks|key|550351|text|您可以使用tonumber函数，就像使用tostring函数一样，下面介绍如何使用它：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|550352|local+x+=+tonumber("45")
print(x)|code-block|syntax|javascript|550353|结果应该是45。|550354|entityMap^0|5|8|K|8|0|0|5|2|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

You can use the <code>tonumber</code> function, just like how you would use the <code>tostring</code> function, here's how do use it:
<pre class="lang-lua prettyprint-override"><code>local x = tonumber(&quot;45&quot;)
print(x)
</code></pre>
The result should be <code>45</code>.

blocks|key|333434|text|下面是你应该放的内容|type|unstyled|depth|inlineStyleRanges|entityRanges|data|333435|local+stringnumber+=+"10"
local+a+=+tonumber(stringnumber)
print(a+%2B+10)

output:

20|code-block|syntax|javascript|333436|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|$]]

here is what you should put

<pre><code>local stringnumber = "10"
local a = tonumber(stringnumber)
print(a + 10)

output:

20
</code></pre>

How can I convert a string to an integer in Lua?

I have a string like this:

<pre><code>a = "10"
</code></pre>

I would like it to be converted to 10, the number.

Lua string to int

Python

如何在Lua中将字符串转换为整数？我有一个这样的字符串：a = "10"我想把它转换成10，这个数字。

问将Lua字符串转换为int
EN

回答 10

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