std :: string要float或double [英] std::string to float or double
本文介绍了std :: string要float或double的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我试图将 std :: string
转换为 float / double
。
我试过:
std :: string num =0.6
double temp =(double)atof(num.c_str());
但它总是返回零。任何其他方式?
解决方案
std :: string num =0.6
double temp = :: atof(num.c_str());对我来说,这是一个有效的C ++语法将字符串转换为双精度。 p>
你可以使用stringstream或boost :: lexical_cast来实现,但那些会带来性能损失。
Ahaha你有一个Qt项目...
QString winOpacity(0.6);
double temp = winOpacity.toDouble();
额外注释:
如果输入数据为 const char *
, QByteArray :: toDouble
会更快。
I'm trying to convert std::string
to float/double
.
I tried:
std::string num = "0.6";
double temp = (double)atof(num.c_str());
But it always returns zero. Any other ways?
解决方案 std::string num = "0.6";
double temp = ::atof(num.c_str());
Does it for me, it is a valid C++ syntax to convert a string to a double.
You can do it with the stringstream or boost::lexical_cast but those come with a performance penalty.
Ahaha you have a Qt project ...
QString winOpacity("0.6");
double temp = winOpacity.toDouble();
Extra note:
If the input data is a const char*
, QByteArray::toDouble
will be faster.
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