C++ 转换不工作

Question

#include <iostream>
using namespace std;
/*Use void functions, they perform some action but do not return a value*/

//Function Protoype, input,read in feet and inches:
void input (double&  feet, double& inches);
//Function Prototype, calculate, calculate with given formulae.
void calculate(double& feet, double& inches);
//Function Prototype, output, outputs calculations to screen.
void output (double meters, double centimeters);  

int main () 
{
    double feet;
    double inches;
    char repeat;

    do
    {
        //Call input:
        input(feet, inches);
        //Call calculate:
        calculate(feet, inches);
        //Call output:
        output (feet, inches);
        cout << "\n";
        cout << "Repeat? (Y/N): ";
        cin >> repeat;
        cout << "\n";
    }
    while (repeat == 'Y' || repeat == 'y');
}

//Input function definition:
void input (double&  feet, double& inches)
{
    cout << "Please enter the length in feet" << endl;
    cin >> feet;

    cout << "Please enter the length in inches" << endl;
    cin >> inches;
}

//Calculate function definition, insert formulae here:
void calculate (double& feet, double& inches)
{

    feet = (feet * 0.3048);
     inches = (inches * 2.54);
}

//Output function definition:
void output (double meters, double centimeters)
{
    cout << meters << " meters & " << centimeters << " cm's. " << endl;
}

为什么我的转换不起作用？ 或者我做错了什么？

目标:给定以英尺和英寸为单位的长度，我想输出以米和厘米为单位的等效长度。

//Calculate function definition, insert formula here:
void calculate (double& feet, double& inches)
{
     feet = (feet * 0.3048);
  inches = (inches * 2.54);
}

Answer 1

这似乎是一种奇怪的做法，它改变了实际的输入变量。我会选择:

void calculate (double feet, double inches, double& meters, double& centimeters) {
    double all_inches = feet * 12.0 + inches;
    centimeters = all_inches * 2.54;
    meters = int (centimeters / 100.0);
    centimeters -= (meters * 100.0);
}

无论如何，即使您确实对输入和输出使用相同的变量(然后应将它们重命名为更合适的名称)，转换为单一形式(英寸)仍然是最简单的) 然后转换为厘米，然后再转换回 m/cm。

在您当前的代码中，如果您传入 1ft,0in，您将返回 0.3048m,0cm，而不是更正确的 30.48cm。通过使用此答案中的代码，它将首先转换为 12.0 英寸，然后从那里转换为 30.48cm，然后转换为 0m,30.48cm。

同样，四英尺半(4ft,6in)将首先转换为 54 英寸，然后转换为 137.16cm，然后转换为 1m,37.16cm。