在C ++使用boost :: lexical_cast的double转换成字符串？ [英] Convert double to string using boost::lexical_cast in C++?

问题描述

我想用的lexical_cast 为浮点转换为字符串。通常它工作正常，但我有一些问题与数字无小数点。如何解决在字符串中显示的小数的号码是多少？

I' d like to use lexical_cast to convert a float to a string. Usually it works fine, but I have some problems with numbers without decimal. How can I fix number of decimal shown in the string?

例如：

double n=5;
string number;
number = boost::lexical_cast<string>(n);

结果数是 5 ，我需要数 5.00 。

推荐答案

从文档的升压lexical_cast的：

对于更复杂的转换，例如在precision或格式需要比由lexical_cast的默认行为提供了更严格的控制，建议常规的stringstream的做法。当转换是数字到数字，numeric_cast可以提供比lexical_cast的更合理的行为。

For more involved conversions, such as where precision or formatting need tighter control than is offered by the default behavior of lexical_cast, the conventional stringstream approach is recommended. Where the conversions are numeric to numeric, numeric_cast may offer more reasonable behavior than lexical_cast.

例如：

#include <sstream>
#include <iomanip>

int main() {
    std::ostringstream ss;
    double x = 5;
    ss << std::fixed << std::setprecision(2);
    ss << x;
    std::string s = ss.str();
    return 0;
}

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