定义一个基类 Animal，其中有一个虚函数 perform()，用于在子类中实现不同的表演行为。

#include <iostream>using namespace std;
class Animal
{
public:Animal() {}virtual void perform(){}
};
class Monkey:public Animal
{
public:Monkey() {}void perform(){cout << "tiao" << endl;}
};
class elephlant:public Animal
{
public:elephlant() {}void perform(){cout << "shuaibizi" << endl;}
};
class lion:public Animal
{
public:lion() {}void perform(){cout << "hong" << endl;}
};
int main()
{Animal *a;Monkey m;elephlant e;lion l;a=&m;a->perform();a=&e;a->perform();a=&l;a->perform();return 0;
}

用函数模板实现不同数据类型的交换功能。

#include <iostream>
#include<iomanip>
using namespace std;
template<typename T,typename Q>
void fun(T &a,Q &b)
{T t=a;a=static_cast<T>(b);b=static_cast<Q>(t);
}
int main()
{int a=10;float b=2.5;fun(a,b);cout << a << setw(5) << fixed << setprecision(1) << b << endl;return 0;
}