将输入字符串转换为float / double C ++ [英] Converting Input string to float/double C++

问题描述

所以我知道如何在C＃中做到这一点，但不懂C ++。我正在尝试将给定用户的输入解析为双精度型（稍后再做数学运算），但是我对C ++不熟悉，遇到了麻烦。

So I know how to do it in C#, but not C++. I am trying to parse giver user input into a double (to do math with later), but I am new to C++ and am having trouble. Help?

C＃

 public static class parse
        {
            public static double StringToInt(string s)
            {
                double line = 0;
                while (!double.TryParse(s, out line))
                {
                    Console.WriteLine("Invalid input.");
                    Console.WriteLine("[The value you entered was not a number!]");
                    s = Console.ReadLine();
                }
                double x = Convert.ToDouble(s);
                return x;
            }
        }

C ++
吗？
？
？
？

C++ ? ? ? ?

推荐答案

看看atof。请注意，atof使用cstrings，而不是字符串类。

Take a look at atof. Note that atof takes cstrings, not the string class.

#include <iostream>
#include <stdlib.h> // atof

using namespace std;

int main() {
    string input;
    cout << "enter number: ";
    cin >> input;
    double result;
    result = atof(input.c_str());
    cout << "You entered " << result << endl;
    return 0;
}

http://www.cplusplus.com/reference/cstdlib/atof/

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