c++ - 错误 : no match for 'operator*' (operand types are 'std: :string {aka std basic_string}' and {aka std basic_string}')

Question

所以我是编程新手，这是大学工程类(class)的一部分。我决定找点乐子，在课外写点东西。我正在尝试用 C++ 编写一个程序，允许用户输入 3 个矩形棱柱的长度、宽度和高度值，程序将使用这 3 个值来计算棱柱的表面积和体积。

这就是我目前所拥有的。 (写在 Vocareum 中)

//---------------------------------------------------------------------------------------// 
//Calculate rectangular prism//        
//---------------------------------------------------------------------------------------//
#include <string>
#include <iostream>  
using namespace std;

int main() 
{
string length; // length of prism in cm 
string width; // width of prism in cm 
string height; // height of prism in cm

cout << "Please enter the length, width, and height of the rectangular prism." << endl; 

cin >> length; //length of prism in cm
cin >> width; //width of prism in cm
cin >> height; //height of prism in cm

double volume; //volume of prism in cm^3
double sa; //surface area of prism in cm^2

volume = length * width * height;
sa = (length * width * 2) + (width * height * 2) + (height * length * 2);

cout << "The volume of the rectangular prism is " << volume << " cm^3." << endl;
cout << "The surface area of the rectangular prism is " << sa << " cm^2." << endl;

return 0;
}

//Whenever I try to compile, I'll get 4 error messages that reads 
//"error: no match for 'operator*' (operand types are 'std: :string {aka std basic_string<char>}' and {aka std basic_string<char>}')
//ps these 3 comments aren't in the code

我该如何解决？

Answer 1

length、width 和 height 变量的类型是 string，不能解释为数字.如果你想让它编译，只需将它们的类型更改为 float 或 double (或 int)