在 C++ 中使用 boost::lexical_cast 将双精度转换为字符串?

问题描述

我想使用 lexical_cast 将浮点数转换为字符串.通常它工作正常，但我对没有小数的数字有一些问题.如何修复字符串中显示的小数位数?

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?

示例:

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

结果编号是5，我需要编号5.00.

Result number is 5, I need number 5.00.

推荐答案

来自 提升 lexical_cast:

对于更复杂的转换，例如需要比 lexical_cast 的默认行为提供的更严格控制的精度或格式，建议使用传统的 stringstream 方法.在数字到数字的转换中，numeric_cast 可能提供比 lexical_cast 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.

示例:

#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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