字符串到双精度转换C ++ [英] String to Double conversion C++

问题描述

我正在尝试将字符串转换为双精度型，但是双精度型会在小数点后第三位被截断。

I'm trying to convert a string into a double but my double gets cut off at the 3rd decimal point.

我的字符串如下所示：-122.39381636393
转换后看起来像这样：-122.394

My string looks like this: "-122.39381636393" After it gets converted it looks like this: -122.394

void setLongitude(string longitude){
    this->longitude = (double)atof(longitude.c_str());

    cout << "got longitude: " << longitude << endl;
    cout << "setting longitude: " << this->longitude << endl;
}

输出示例：

got longitude: -122.39381636393
setting longitude: -122.394

我希望它保留所有小数点，还有什么提示吗？

I want it to maintain all the decimal points, any tips?

推荐答案

如果我是您：

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string str = "-122.39381636393";
    std::cout.precision(20);
    cout << "setting longitude: " << stod(str) << endl;
    return 0;
}

基本上，您会更改以下内容：

Basically, you would change things like:

• 打印精度

• precision for the printing

存储而不是低级操作来获得双精度

stod rather than low-level operation to get the double back from the string.

您可以看到它在运行ideone上。

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