本文主要是介绍第4天C++练习，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
#include <iostream>
using namespace std;class Human{private:string name;int age;public:Human(){cout<<"human的无参构造函数"<<endl;}Human(string n,int a):name(n),age(a){cout<<"human的有参构造函数"<<endl;}~Human(){cout<<"human的析构函数"<<endl;}void show(){cout<<"human的show()"<<endl;cout<<"human::"<<"姓名:"<<name<<" 年龄:"<<age<<endl;}void setName(string n){name=n;}
};//学生类
class Student:virtual public Human
{private:double score;public:Student(){cout<<"student的无参构造函数"<<endl;}Student(string n,int a,double s):Human(n,a),score(s){cout<<"student的有参构造函数"<<endl;}~Student(){cout<<"student的析构函数"<<endl;}void show(){cout<<"student的show()"<<endl;Human::show();cout<<"成绩:"<<score<<endl;}void show(string s){cout<<"student的show()"<<endl;if(s=="score") {cout<<"成绩:"<<score<<endl;return ;}Human::show();cout<<"成绩:"<<score<<endl;}void setScore(double s){score=s;}
};//党员类
class Party:virtual public Human{private:string activity; //党组织活动string party;public:Party(){cout<<"party的无参构造函数"<<endl;}Party(string n,int a,string act,string p):Human(n,a),activity(act),party(p){cout<<"party的有参构造函数"<<endl;}~Party(){cout<<"party的析构函数"<<endl;}void show(){cout<<"part的show()"<<endl;Human::show();cout<<"党组织活动:"<<activity<<" 党派:"<<party<<endl;}void show(string s){cout<<"part的show()"<<endl;if(s == "party"){cout<<"党派:"<<party<<endl;return ;}Human::show();cout<<"党组织活动:"<<activity<<" 党派:"<<party<<endl;}
};//学生干部
class StudentCadre:public Student,public Party{private:string position;//职务public:StudentCadre(){cout<<"studentcadre的无参构造函数"<<endl;}StudentCadre(string n,int a,double s,string act,string p,string pos):Human(n,a),Student(n,a,s),Party(n,a,act,p),position(pos){cout<<"studentcadre的有参构造函数"<<endl;}~StudentCadre(){cout<<"studentcadre的析构函数"<<endl;}void show(){cout<<"studentcadre的show()"<<endl;Human::show();Student::show("score");Party::show("party"); cout<<"职务:"<<position<<endl;}
};int main()
{StudentCadre sc("张三",18,90,"党员活动","共产党","班长");cout<<" sizeof(sc) = "<< sizeof(sc)<<endl;sc.show();return 0;
} 
对于函数模板和类模板来说，它们的实现机制主要依赖于编译器在编译时期生成特定类型的代码。这意味着对于每一种需要的类型，编译器都会生成一个模板的实例。例如，如果你有一个函数模板 max 并且用 int 和 double 类型调用了它，编译器将生成两个不同的函数版本，一个用于 int 类型，另一个用于 double 类型。
这种实例化是在编译时完成的，因此不会影响运行时性能。但是，它可能会增加编译时间和生成的代码量，因为每个实例都是独立的函数或类。
#include "iostream"
#include "cmath"
using namespace std;class graphical{protected:float perm;float area;public:float get_perm(){return perm;}float get_area(){return area ;}
};class rectangle:public graphical{private:float length;float wide;public:rectangle(float l,float w){length = l;wide = w;perm = 2*(length+wide);area = length*wide;}
};class circle:public graphical{private:float radius;public:circle(float r){radius = r;perm = 2*3.14*radius;area = 3.14*radius*radius;}
};//定义三角形类
class triangle:public graphical{private:float a;float b;float c;public:triangle(float a,float b,float c){this->a = a;this->b = b;this->c = c;perm = a+b+c;area = sqrt((a+b+c)*(a+b-c)*(a+c-b)*(b+c-a))/4;}
};//定义一个全局函数，出入任意一个图形，输出该图形的周长和面积
void func(graphical &g)
{cout << "周长：" << g.get_perm() << endl;cout << "面积：" << g.get_area() << endl;
}int main()
{rectangle r(3,4);circle c(5);triangle t(3,4,5);func(r);func(c);func(t);return 0;
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