blocks|key|4707504|text|atof()|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4707505|(或者std::atof()+talking+C%2B%2B+--感谢jons34yp)|style|CODE|4707506|entityMap|0|LINK|mutability|MUTABLE|url|http://www.cplusplus.com/reference/clibrary/cstdlib/atof/|1|http://en.cppreference.com/w/cpp/string/byte/atof|2|https://stackoverflow.com/users/283145/jons34yp^0|0|6|0|0|3|B|3|B|1|V|8|2|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|D|3|E|5|6|7|X|8|@$A|Y|B|Z|F|G]]|9|@$A|10|B|11|1|12]|$A|13|B|14|1|15]]|C|$]]|$1|H|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]|P|$5|K|L|M|C|$N|Q]]|R|$5|K|L|M|C|$N|S]]]]

<a href="http://www.cplusplus.com/reference/clibrary/cstdlib/atof/" rel="noreferrer">atof()</a>

(or <a href="http://en.cppreference.com/w/cpp/string/byte/atof" rel="noreferrer"><code>std::atof()</code></a> talking C++ - thanks <a href="https://stackoverflow.com/users/283145/jons34yp">jons34yp</a>)

blocks|key|1040685|text|#include+<stdlib.h>
double+atof(const+char*);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1040686|还有strtod。|unstyled|offset|length|style|CODE|1040687|entityMap^0|0|2|6|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>#include &lt;stdlib.h&gt;
double atof(const char*);
</code></pre>

There's also <code>strtod</code>.

blocks|key|4707556|text|strtof|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4707557|从手册页|4707558|strtod()、strtof()和strtod()函数分别将nptr指向的字符串的初始部分转换为双精度、浮点数和长双精度表示。|4707559|字符串(的初始部分)的预期形式是由isspace(3)识别的可选的前导空格、可选的加号(‘’%2B‘’)或减号(‘’-‘’)，然后是(i)十进制数，或(ii)十六进制数，或(iii)无穷大，或(iv)+NAN+(非数字)。|4707560|/man+page>|4707561|atof将字符串转换为双精度型(而不是顾名思义的浮点型)。|4707562|entityMap^0|0|6|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|W|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|X|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|Y|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|Q|$]]

<code>strtof</code>

From the man page

The strtod(), strtof(), and strtold() functions convert the initial portion of the string pointed to by nptr to double, float, and long double representation, respectively.

The expected form of the (initial portion of the) string is optional leading white space as recognized by isspace(3), an optional plus (‘‘+’’) or minus sign (‘‘-’’) and then either (i) a decimal number, or (ii) a hexadecimal number, or (iii) an infinity, or (iv) a NAN (not-a-number).

/man page>

atof converts a string to a double (not a float as it's name would suggest.)

blocks|key|3107189|text|使用stdlib.h中的atof|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3107190|double+atof+(+const+char+*+str+);|code-block|syntax|javascript|3107191|entityMap^0|2|8|C|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Use <code>atof</code> from <code>stdlib.h</code>:

<pre><code>double atof ( const char * str );
</code></pre>

blocks|key|4707581|text|更喜欢strtof()。atof()不检测错误。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4707582|entityMap^0|3|8|C|6|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|$]]

Prefer <code>strtof()</code>. <code>atof()</code> does not detect errors.

blocks|key|1873613|text|boost::lexical_cast<float>(str);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1873614|这个模板函数包含在流行的Boost库集合中，如果您对C%2B%2B很感兴趣，就会想要了解它。|unstyled|offset|length|1873615|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_45_0/libs/conversion/lexical_cast.htm^0|0|C|5|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>boost::lexical_cast&lt;float&gt;(str);
</code></pre>

This template function is included in the popular <a href="http://www.boost.org/doc/libs/1_45_0/libs/conversion/lexical_cast.htm">Boost</a> collection of libraries, which you'll want learn about if you're serious about C++.

blocks|key|1040800|text|将字符串转换为任何类型(即默认可构造和可流式处理)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1040801|template<+typename+T+>
T+convert_from_string(const+std::string&+str)
{
++std::istringstream+iss(str);
++T+result;
++if(+!(iss+>>+result)+)+throw+"Dude,+you+need+error+handling!";
++return+result;
}|code-block|syntax|javascript|1040802|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|$]]

Convert a string to any type (that's default-constructible and streamable): 

<pre><code>template&lt; typename T &gt;
T convert_from_string(const std::string&amp; str)
{
 std::istringstream iss(str);
 T result;
 if( !(iss &gt;&gt; result) ) throw "Dude, you need error handling!";
 return result;
}
</code></pre>

blocks|key|1869560|text|作为已经提到的std::strtof()和boost::lexical_cast<float>()的替代方案，新的C%2B%2B标准引入了|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1869561|float+stof(const+string&+str,+size_t+*idx+=+0);
double+stod(const+string&+str,+size_t+*idx+=+0);
long+double+stold(const+string&+str,+size_t+*idx+=+0);|code-block|syntax|javascript|1869562|用于错误检查字符串到浮点的转换。GCC和微软微软视频都支持它们(记住#include+<string>)|1869563|entityMap^0|7|D|L|S|0|0|Y|H|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|$]]

As an alternative to the the already-mentioned <code>std::strtof()</code> and <code>boost::lexical_cast&lt;float&gt;()</code>, the new C++ standard introduced 

<pre><code>float stof(const string&amp; str, size_t *idx = 0);
double stod(const string&amp; str, size_t *idx = 0);
long double stold(const string&amp; str, size_t *idx = 0);
</code></pre>

for error-checking string to floating-point conversions. Both GCC and MSVC support them (remember to <code>#include &lt;string&gt;</code>)

blocks|key|3107302|text|这也可以工作(但C类代码)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3107303|#include+<iostream>

using+namespace+std;

int+main()
{
float+myFloatNumber+=+0;
string+inputString+=+"23.2445";
sscanf(inputString.c_str(),+"%25f",+&myFloatNumber);
cout<<+myFloatNumber+*+100;

}|code-block|syntax|javascript|3107304|点击这里查看：http://codepad.org/qlHe5b2k|offset|length|3107305|entityMap|0|LINK|mutability|MUTABLE|url|http://codepad.org/qlHe5b2k^0|0|0|7|R|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

This would also work ( but C kind of code ):

<pre><code>#include &lt;iostream&gt;

using namespace std;

int main()
{
float myFloatNumber = 0;
string inputString = "23.2445";
sscanf(inputString.c_str(), "%f", &amp;myFloatNumber);
cout&lt;&lt; myFloatNumber * 100;

}
</code></pre>

See it here:
<a href="http://codepad.org/qlHe5b2k" rel="nofollow">http://codepad.org/qlHe5b2k</a>

blocks|key|3107325|text|作为上述所有方法的替代，您可以使用字符串流。http://cplusplus.com/reference/iostream/stringstream/|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3107326|entityMap|0|LINK|mutability|MUTABLE|url|http://cplusplus.com/reference/iostream/stringstream/^0|M|1H|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

As an alternative to all above, you may use string stream.
<a href="http://cplusplus.com/reference/iostream/stringstream/" rel="nofollow">http://cplusplus.com/reference/iostream/stringstream/</a>

blocks|key|1869600|text|试试boost::spirit:快速，类型安全，非常高效：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1869601|std::string::iterator+begin+=+input.begin();
std::string::iterator+end+=+input.end();
using+boost::spirit::float_;

float+val;
boost::spirit::qi::parse(begin,end,float_,val);|code-block|syntax|javascript|1869602|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 boost::spirit: fast, type-safe and very efficient:

<pre><code>std::string::iterator begin = input.begin();
std::string::iterator end = input.end();
using boost::spirit::float_;

float val;
boost::spirit::qi::parse(begin,end,float_,val);
</code></pre>

Is there a function similar to atoi which converts a string to float instead of to integer?

like atoi but to float

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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有没有类似atoi的函数可以将字符串转换为浮点型而不是整型？

问像atoi一样，但要浮动
EN

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问像atoi一样，但要浮动EN