如何以可读格式打印双精度？

a = 3.14159
b = float(a)
print(b)  # 输出结果为 3.141590000

from decimal import Decimal

a = 3.14159
b = Decimal(a)
print(b)  # 输出结果为 Decimal('3.14159')

#include <iostream>
#include <string>
#include <stdexcept>

int main() {
    std::string str = "3.14159";
    try {
        double num = std::stod(str);
        std::cout << num << std::endl;
    } catch (const std::invalid_argument &e) {
        std::cerr << "Invalid argument: " << e.what() << std::endl;
    } catch (const std::out_of_range &e) {
        std::cerr << "Out of range: " << e.what() << std::endl;
    }
    return 0;
}