Float-to-string转换引发异常而不是像atof那样返回0.0 [英] Float-to-string conversion that raises exception instead of returning0.0 like atof
问题描述
嗨！
愚蠢的atof，当它试图解析类似
" fish"之类的东西时返回0.0。所以我不知道这个数字是真的是0还是一个字符串
无法解析。还有更好的办法吗？
Trond Valen
Hi!
Stupid atof, it returns 0.0 when it tries to parse something like
"fish". So I don''t know whether the number was really 0 or a string that
couldn''t be parsed. Is there a better way to do this?
Trond Valen
推荐答案
Trond Valen写道：
Trond Valen wrote:
嗨！
愚蠢的atof，它在尝试解析类似
fish的东西时返回0.0。所以我不知道这个数字是真的是0还是一个无法解析的字符串。有更好的方法吗？
Hi!
Stupid atof, it returns 0.0 when it tries to parse something like
"fish". So I don''t know whether the number was really 0 or a string that
couldn''t be parsed. Is there a better way to do this?
#include< sstream>
#include< string>
< br $>
class bad_float {};
float string_to_float（const std :: string& s）
{
std :: istringstream iss（s）;
浮动f;
iss>> f;
if（！iss）throw bad_float（）;
return f;
}
Jonathan
# include <sstream>
# include <string>
class bad_float {};
float string_to_float(const std::string &s)
{
std::istringstream iss(s);
float f;
iss >> f;
if (!iss) throw bad_float();
return f;
}
Jonathan
Trond Valen写道：
Trond Valen wrote:
嗨！
愚蠢的atof，它在尝试解析类似
fish的东西时返回0.0。所以我不知道这个数字是真的是0还是一个无法解析的字符串。有更好的方法吗？
Hi!
Stupid atof, it returns 0.0 when it tries to parse something like
"fish". So I don''t know whether the number was really 0 or a string that
couldn''t be parsed. Is there a better way to do this?
确实是愚蠢的。但回答你的问题：是的，有更好的方法。
使用来自< sstream>的C ++字符串流或使用strtod（和strtol代替
of atoi）可以区分零和错误情况。
Gavin Deane
Stupid indeed. But to answer your question: yes, there is a better way.
Use C++ stringstreams from <sstream> or use strtod (and strtol instead
of atoi) which can distinguish between zero and an error case.
Gavin Deane
Jonathan Mcdougall写道：
Jonathan Mcdougall wrote:
Trond Valen写道：
Trond Valen wrote:
嗨！
愚蠢atof，当它试图解析类似
fish的东西时，它返回0.0。所以我不知道这个数字是真的是0还是一个无法解析的字符串。有没有更好的方法呢？
Hi!
Stupid atof, it returns 0.0 when it tries to parse something like
"fish". So I don''t know whether the number was really 0 or a string that
couldn''t be parsed. Is there a better way to do this?
#include< sstream>
#include< string>
class bad_float {};
float string_to_float（const std :: string& s）
{st / :: istringstream iss（s）;
float f;
iss >> f;
if（！iss）throw bad_float（）;
返回f;
}
Jonathan
# include <sstream>
# include <string>
class bad_float {};
float string_to_float(const std::string &s)
{
std::istringstream iss(s);
float f;
iss >> f;
if (!iss) throw bad_float();
return f;
}
Jonathan
谢谢:)
Thanks :)
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