你只是犯了一个愚蠢的错误。你在接受用户输入之前调用了'ConeVolume'函数。所以，只有垃圾值被传递给了函数。

# include <iostream>
# include <string.h>
# include <string>

using namespace std;

// ConeVolume prototype
float ConeVolume(float radius, float height);

int main()
{
    // Establish variables 
    float radius1;
    float height2;

    //wrong code here
    // you've called the function before taking input of radius1 and height2
    //float volumeCone = ConeVolume(radius1, height2);

    // User input to define the varibales
    cout << "Radius: ";
    cin >> radius1;
    cout << "Height: ";
    cin >> height2;

    // Correct code:
    // Call the function after taking input
    float volumeCone = ConeVolume(radius1, height2);

    // Return variable using the ConeVolume function
    cout << endl << "Cone Volume: " << volumeCone;

    return 0;
}

// Function that calculates the volume of a Cone
float ConeVolume(float radius, float height)
{
    float pi = 3.14;
    float volume = (pi/3)*(radius * radius) * (height);
    
    return volume;
}

希望这个有用。

程序返回0，因为在更改radius1和height2的值后，volumeCone的值没有更新。
必须再次调用函数coneVolume()，或者最好在定义了radius1和height2之后调用它。

int main()
{
    // Establish variables 
    float radius1;
    float height2;

    // User input to define the varibales
    cout << "Radius: ";
    cin >> radius1;
    cout << "Height: ";
    cin >> height2;

    float volumeCone = ConeVolume(radius1, height2);

    // Return variable using the ConeVolume function
    cout << endl << "Cone Volume: " << volumeCone;

    return 0;
}

插入行
体积圆锥体=圆锥体体积（半径1，高度2）;
线后
cin〉〉高度2;
然后换线
浮子体积锥=锥体积（半径1，高度2）;
到
浮子容积锥;
。