[英]Choose class depending on external input in C++
在我的程序中,我有幾個不同的類,其中包含一個具有相同名稱但輸出不同的函數:
#include <iostream>
#define CLASS_TO_USE C
class A{
public:
std::string class_name = "Class A";
A()
{};
double add(const double a, const double b) const
{
return a + b;
}
};
class B{
public:
std::string class_name = "Class B";
B()
{};
double add(const double a, const double b) const
{
return 2 * a + b;
}
};
class C{
public:
std::string class_name = "Class C";
C()
{};
double add(const double a, const double b) const
{
return 3 * a + b;
}
};
template <class T>
void calculate_addition(const T &local_class, const double a, const double b)
{
std::cout << "Addition gives the value " << local_class.add(a, b) << '\n';
}
int main()
{
CLASS_TO_USE local_class;
std::cout << "Hello World!" << std::endl;
calculate_addition(local_class, 2, 3);
return 0;
}
當前,我通過更改CLASS_TO_USE
的變量在這些類之間切換,但是該方法需要重新編譯,這需要一些時間。 我寧願選擇一種在運行時也可以使用的方法,即可以在其中使用f.ex的方法。 用戶的輸入。 有可能嗎?如果可以,怎么辦?
編輯:我使用以下代碼解決了問題:
#include <iostream>
#include <variant>
class A{
public:
std::string class_name_string = "Class A";
A()
{};
virtual double add(const double a, const double b) const
{
(void) a;
(void) b;
return 0;
};
virtual std::string class_name(void) const
{
return class_name_string;
}
};
class B : public A{
public:
std::string class_name_string = "Class B";
B()
{};
double add(const double a, const double b) const
{
return 2 * a + b;
}
virtual std::string class_name(void) const
{
return class_name_string;
}
};
class C : public A{
public:
std::string class_name_string = "Class C";
C()
{};
double add(const double a, const double b) const
{
return 3 * a + b;
}
virtual std::string class_name(void) const
{
return class_name_string;
}
};
class D : public A{
public:
std::string class_name_string = "Class D";
D()
{};
double add(const double a, const double b) const
{
return a + b;
}
virtual std::string class_name(void) const
{
return class_name_string;
}
};
void calculate_base_addition(const A &local_class, const double a, const double b)
{
std::cout << "Addition gives the value " << local_class.add(a, b) << " by using " << local_class.class_name() << '\n';
}
int main()
{
A *base_class;
B tmp_class_B;
C tmp_class_C;
D tmp_class_D;
int class_to_choose = 2;
switch(class_to_choose)
{
case 0:
{
base_class = &tmp_class_B;
break;
}
case 1:
{
base_class = &tmp_class_C;
break;
}
case 2:
default:
{
base_class = &tmp_class_D;
break;
}
}
std::cout << "Name of base_class: " << (*base_class).class_name() << '\n';
std::cout << "Name of derived class: " << tmp_class_B.class_name() << '\n';
std::cout << "Hello World!" << std::endl;
calculate_base_addition(*base_class, 2, 3);
return 0;
}
並在此處有一個后續問題: 根據用戶輸入在類中定義類變量
您可以分派整數用戶輸入,例如:
int choice;
std::cin >> choice;
switch (choice)
{
case 1:
calculate_addition(A(), 2, 3);
break;
case 2:
calculate_addition(B(), 2, 3);
break;
case 3:
default:
calculate_addition(C(), 2, 3);
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.