c++ - 从创建的类中获取用户输入
问题描述
我是编程新手,我在 24 小时内一直在阅读 Sams Teach Yourself C++。我刚开始学习课程,对如何允许用户输入私人数据感到困惑。我创建了以下返回梯形面积的类。任何建议将不胜感激。
class Trapezoid
{
//assigns a number to a variable
private:
int a = 20;
int b = 25;
int height = 30;
int area;
public:
int getArea();
};
int Trapezoid::getArea()
{
// calculates the area and returns it.
area = (a + b) / 2 + height;
return area;
}
#include "AreaTrapezoid.hpp"
#include <iostream>
int main()
{
// accesses area inside the Trapeziod class.
Trapezoid areaT;
areaT.getArea();
// displays the area result
std::cout << "The area of a Trapezoid: " << areaT.getArea() << std::endl;
std::cout << system("pause");
return 0;
}
解决方案
您需要阅读用户的输入,然后公开公共访问权限以将新值分配给类的私有成员。例如:
class Trapezoid
{
//assigns a number to a variable
private:
int a = 20;
int b = 25;
int height = 30;
public:
int getArea();
void setA(int value);
void setB(int value);
void setHeight(int value);
};
int Trapezoid::getArea()
{
// calculates the area and returns it.
return (a + b) / 2 + height;
}
void Trapezoid::setA(int value)
{
a = value;
}
void Trapezoid::setB(int value);
{
b = value;
}
void Trapezoid::setHeight(int value)
{
height = value;
}
#include <iostream>
#include <limits>
#include <cstdlib>
#include "AreaTrapezoid.hpp"
int main()
{
Trapezoid areaT;
int value;
// get the user's input and apply it to the Trapeziod.
std::cout << "Enter A: ";
std::cin >> value;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
areaT.setA(value);
std::cout << "Enter B: ";
std::cin >> value;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
areaT.setB(value);
std::cout << "Enter Height: ";
std::cin >> value;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
areaT.setHeight(value);
// displays the area result
std::cout << "The area of the Trapezoid: " << areaT.getArea() << std::endl;
std::system("pause");
return 0;
}
或者,改用构造函数:
class Trapezoid
{
//assigns a number to a variable
private:
int a;
int b;
int height;
public:
Trapezoid(int a, int b, int height);
int getArea();
};
Trapezoid::Trapezoid(int a, int b, int height)
: a(a), b(b), height(height)
{
}
int Trapezoid::getArea()
{
// calculates the area and returns it.
return (a + b) / 2 + height;
}
#include <iostream>
#include <limits>
#include <cstdlib>
#include "AreaTrapezoid.hpp"
int main()
{
int a, b, h;
// get the user's input and apply it to the Trapeziod.
std::cout << "Enter A: ";
std::cin >> a;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
std::cout << "Enter B: ";
std::cin >> b;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
areaT.setB(value);
std::cout << "Enter Height: ";
std::cin >> h;
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
// displays the area result
Trapezoid areaT(a, b, h);
std::cout << "The area of the Trapezoid: " << areaT.getArea() << std::endl;
std::system("pause");
return 0;
}
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