C ++字符串到双精度转换

问题描述

通常当我在C ++中写任何东西，并且我需要将 char 转换为 int new int 等于char。

Usually when I write anything in C++ and I need to convert a char into an int I simply make a new int equal to the char.

我使用的代码（snippet）

I used the code(snippet)

 string word;
 openfile >> word;
 double lol=word;

我收到错误

Code1.cpp cannot convert `std::string' to `double' in initialization

错误是什么意思？第一个字是数字50.谢谢：）

What does the error mean exactly? The first word is the number 50. Thanks :)

推荐答案

您可以将char转换为int和反之亦然， int和char是相同的，8位，唯一的区别是当他们必须在屏幕上显示，如果数字是65，并保存为一个字符，那么它将显示'A'，如果它保存为一个int它将显示65.

You can convert char to int and viceversa easily because for the machine an int and a char are the same, 8 bits, the only difference comes when they have to be shown in screen, if the number is 65 and is saved as a char, then it will show 'A', if it's saved as a int it will show 65.

对于其他类型的东西会改变，因为它们在内存中的存储方式不同。在C中有标准函数，它允许你从字符串转换为double容易，它的atof。 （您需要包含stdlib.h）

With other types things change, because they are stored differently in memory. There's standard function in C that allows you to convert from string to double easily, it's atof. (You need to include stdlib.h)

#include <stdlib.h>

int main()
{
    string word;
    openfile >> word;
    double lol = atof(word.c_str()); /*c_str is needed to convert string to const char*
                                     previously (the function requires it)*/
    return 0;
}

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