遗产:
继承是在其中创建一个新类的继承,新类继承已存在的类的属性。它支持代码可重用性的概念,并减少了面向对象编程中代码的长度。
继承的类型有:
- 单继承
- 多级继承
- 多重继承
- 混合继承
- 层次继承
继承示例:
C++
#include "iostream"
using namespace std;
class A {
int a, b;
public:
void add(int x, int y)
{
a = x;
b = y;
cout << (a + b) << endl;
}
};
class B : public A {
public:
void print(int x, int y)
{
add(x, y);
}
};
int main()
{
B b1;
b1.print(5, 6);
}
Java
class A {
int a, b;
public void add(int x, int y)
{
a = x;
b = y;
System.out.println("addition of a + b is:" + (a + b));
}
}
class B extends A {
public void sum(int x, int y)
{
add(x, y);
}
// Driver Code
public static void main(String[] args)
{
B b1 = new B();
b1.sum(5, 6);
}
}
C++
#include "iostream"
using namespace std;
class A {
int a, b, c;
public:
void add(int x, int y)
{
a = x;
b = y;
cout << "addition of a+b is:" << (a + b) << endl;
}
void add(int x, int y, int z)
{
a = x;
b = y;
c = z;
cout << "addition of a+b+c is:" << (a + b + c) << endl;
}
void print()
{
cout << "Class A's method is running" << endl;
}
};
class B : public A {
public:
void print()
{
cout << "Class B's method is running" << endl;
}
};
int main()
{
A a1;
// method overloading (Compile-time polymorphism)
a1.add(6, 5);
// method overloading (Compile-time polymorphism)
a1.add(1, 2, 3);
B b1;
// Method overriding (Run-time polymorphism)
b1.print();
}
Java
class A {
int a, b, c;
public void add(int x, int y)
{
a = x;
b = y;
System.out.println("addition of a+b is:" + (a + b));
}
public void add(int x, int y, int z)
{
a = x;
b = y;
c = z;
System.out.println("addition of a+b+c is:" + (a + b + c));
}
public void print()
{
System.out.println("Class A's method is running");
}
};
class B extends A {
public void print()
{
System.out.println("Class B's method is running");
}
// Driver Code
public static void main(String[] args)
{
A a1 = new A();
// method overloading (Compile-time polymorphism)
a1.add(6, 5);
// method overloading (Compile-time polymorphism)
a1.add(1, 2, 3);
B b1 = new B();
// Method overriding (Run-time polymorphism)
b1.print();
}
}
输出:
addition of a+b is:11
在这里,类B是继承基类A的属性( add方法)的派生类。
多态性:
多态是我们可以以多种形式或方式执行任务的方式。它适用于功能或方法。多态性允许对象决定在编译时以及在运行时实现哪种形式的函数。
多态的类型有:
- 编译时多态(方法重载)
- 运行时多态(方法覆盖)
多态的示例:
C++
#include "iostream"
using namespace std;
class A {
int a, b, c;
public:
void add(int x, int y)
{
a = x;
b = y;
cout << "addition of a+b is:" << (a + b) << endl;
}
void add(int x, int y, int z)
{
a = x;
b = y;
c = z;
cout << "addition of a+b+c is:" << (a + b + c) << endl;
}
void print()
{
cout << "Class A's method is running" << endl;
}
};
class B : public A {
public:
void print()
{
cout << "Class B's method is running" << endl;
}
};
int main()
{
A a1;
// method overloading (Compile-time polymorphism)
a1.add(6, 5);
// method overloading (Compile-time polymorphism)
a1.add(1, 2, 3);
B b1;
// Method overriding (Run-time polymorphism)
b1.print();
}
Java
class A {
int a, b, c;
public void add(int x, int y)
{
a = x;
b = y;
System.out.println("addition of a+b is:" + (a + b));
}
public void add(int x, int y, int z)
{
a = x;
b = y;
c = z;
System.out.println("addition of a+b+c is:" + (a + b + c));
}
public void print()
{
System.out.println("Class A's method is running");
}
};
class B extends A {
public void print()
{
System.out.println("Class B's method is running");
}
// Driver Code
public static void main(String[] args)
{
A a1 = new A();
// method overloading (Compile-time polymorphism)
a1.add(6, 5);
// method overloading (Compile-time polymorphism)
a1.add(1, 2, 3);
B b1 = new B();
// Method overriding (Run-time polymorphism)
b1.print();
}
}
输出:
addition of a+b is:11
addition of a+b+c is:6
Class B's method is running
继承与多态之间的区别:
S.NO | Inheritance | Polymorphism |
---|---|---|
1. | Inheritance is one in which a new class is created (derived class) that inherits the features from the already existing class(Base class). | Whereas polymorphism is that which can be defined in multiple forms. |
2. | It is basically applied to classes. | Whereas it is basically applied to functions or methods. |
3. | Inheritance supports the concept of reusability and reduces code length in object-oriented programming. | Polymorphism allows the object to decide which form of the function to implement at compile-time (overloading) as well as run-time (overriding). |
4. | Inheritance can be single, hybrid, multiple, hierarchical and multilevel inheritance. | Whereas it can be compiled-time polymorphism (overload) as well as run-time polymorphism (overriding). |
5. | It is used in pattern designing. | While it is also used in pattern designing. |
要从最佳影片策划和实践问题去学习,检查了C++基础课程为基础,以先进的C++和C++ STL课程基础加上STL。要完成从学习语言到DS Algo等的更多准备工作,请参阅“完整面试准备课程” 。