C++实验三 | 易学教程

实验结论：

1）Part1 验证性内容：以多文件结构组织的项目文件示例：在画布上可以上下左右移动的小球

Ctrl C+V之后编译运行出现了如下界面：

（假装有图片）

2）Part2 基于已有信息，补足并扩充程序。在graph文件夹里提供有三个文件： graph.h (类Graph的声明) graph.cpp (类Graph的实现) main.cpp (类Graph的测试：定义Graph类对象，调用绘图接口绘制图形)

graph.h

#if !defined GRAPH_H
#define GRAPH_H
 
class Graph {
    public:
        Graph(char ch, int n);   
        void draw();    
    private:
        char symbol;
        int size;
};
 
 
#endif

View Code

graph.cpp

#include <iostream>
#include "graph.h"
using namespace std;
 
int main() {
    Graph graph1('*',5);
    graph1.draw();
     
    system("pause");
    system("cls");
     
    Graph graph2('$',7);
    graph2.draw();
    system("pause");
    return 0;
}

View Code

main.cpp

#include "graph.h"
#include <iostream>
using namespace std;
 
Graph::Graph(char ch,int n):symbol(ch),size(n){
}
 
void Graph::draw(){
    int i,j,k;
    for(i=1;i<=size;i++){ 
    for(j=1;j<=size-i;j++)
    cout<<' ';
    for(k=1;k<=2*i-1;k++)
    cout<<symbol;
    cout<<endl;
  }    
}

View Code

(继续假装有图片)

3）Part3 基于需求描述设计、定义并实现分数类Fraction,并编写代码完成测试。具体要求如下: 设计一个分数类 Fraction描述分数（两个整数的比值）

Fraction.h

#if !defined(FRACTION_H)
#define FRACTION_H

#include<iostream>
#include<stdlib.h>
using namespace std;

namespace std{
    class Fraction{
        private:
            long num,den;
        public:
            Fraction(long p=0,long q=1);
            friend istream& operator>>(istream& istr,Fraction& x);
            Fraction operator+(Fraction& x)const;
            Fraction operator-(Fraction& x)const;
            Fraction operator*(Fraction& x)const;
            Fraction operator/(Fraction& x)const;
            Fraction operator-()const;
            int operator<(Fraction& x)const;
            int operator<=(Fraction& x)const;
            int operator>(Fraction& x)const;
            int operator>=(Fraction& x)const;
            int operator==(Fraction& x)const;
            int operator!=(Fraction& x)const;
            int getnum()const{
            return num;}
            int getden()const{
            return den;}
            void standardize(void);
            long gcd(long m,long n)const;
            void reduce();
    };
    
    Fraction::Fraction(long p,long q):num(p),den(q){
        if(den==0){
            cerr<<"分母不能为 0 ！"<<endl;
            exit(1);
        }
            standardize();
            reduce(); 
    }
    
    void Fraction::standardize(){
        if(den<0){
            num=-num;
            den=-den;
        }
    }
    
    long Fraction::gcd(long m,long n)const{
        static long x;
        if(m>n){
            if(n==0)
            x=m;
            else
            gcd(n,m%n);
        }
        else{
            if(m==0)
            x=n;
            else
            gcd(m,n%m);
        }
        return x;
    }
    
    istream& operator>>(istream& istr,Fraction& x){
        char c;
        istr>>x.num>>c>>x.den;
        if(x.den==0){
            cerr<<"分母不为 0 ！"<<endl;
            exit(1); 
        }
        x.standardize();
        x.reduce();
        return istr;
    }
    
    ostream& operator<<(ostream& ostr,const Fraction& x){
        ostr<<x.getnum()<<'/'<<x.getden();
        return ostr;
    }
    
    Fraction Fraction::operator+(Fraction& x)const{
    Fraction temp=Fraction(num*x.den+den*x.num,den*x.den);
    temp.reduce();
    return temp;
    }
    
    Fraction Fraction::operator-(Fraction& x)const{
    Fraction temp=Fraction(num*x.den-den*x.num,den*x.den);
    temp.reduce();
    return temp;
    }
    
    Fraction Fraction::operator*(Fraction& x)const{
    Fraction temp=Fraction(num*x.num,den*x.den);
    temp.reduce();
    return temp;
    }
    
    Fraction Fraction::operator/(Fraction& x)const{
    Fraction temp=Fraction(num*x.den,den*x.num);
    temp.standardize();
    temp.reduce();
    return temp;
    }
    
    Fraction Fraction::operator-()const{
    return Fraction(-num,den);
    }
    
    int Fraction::operator<(Fraction& x)const{
    return(num*x.getden()<den*x.getnum());
    }
    
    int Fraction::operator<=(Fraction& x)const{
    return(num*x.getden()<=den*x.getnum());
    }
    
    int Fraction::operator==(Fraction& x)const{
    return(num*x.getden()==den*x.getnum());
    }
    
    int Fraction::operator!=(Fraction& x)const{
    return(num*x.getden()!=den*x.getnum());
    }
    
    int Fraction::operator>(Fraction& x)const{
    return(num*x.getden()>den*x.getnum());
    }
    
    int Fraction::operator>=(Fraction& x)const{
    return(num*x.getden()>=den*x.getnum());
    }
    
    void Fraction::reduce(){
        long bigdivisor,tempnumerator;
        tempnumerator=(num<0)?-num:num;
        if(num==0)
        den=1;
        else{
            bigdivisor=gcd(tempnumerator,den);
            if(bigdivisor>1){
                num/=bigdivisor;
                den/=bigdivisor;
                
            }
        }
    }
/*    加加改改 可以输出带分数 
    void print(Fraction x){
        long wholepart=long(x.getnum()/x.getden());
        Fraction fractionpart=x-Fraction(wholepart);
        if(fractionpart==Fraction(0L))
        cout<<wholepart<<" ";
        else{
            fractionpart.reduce();
            if(wholepart<0)
            fractionpart=-fractionpart;
            if(wholepart!=0)
            cout<<wholepart<<" "<<fractionpart<<" ";
            else
            cout<<fractionpart<<" ";
        }
    }
*/
}

#endif

View Code

main.cpp

#include"Fraction.h"
int main(){
    Fraction r1,r2;
    cout<<"输入两个分数："<<endl;
    cin>>r1>>r2;
    if(r1<r2)
    cout<<r1<<"<"<<r2<<endl;
    else if(r1==r2)
    cout<<r1<<"=="<<r2<<endl;
    else
    cout<<r1<<">"<<r2<<endl;
    cout<<"和为： "<<r1+r2<<endl;
    cout<<"积为： "<<r1*r2<<endl;
    cout<<"差为： "<<r1-r2<<endl;
    cout<<"商为： "<<r1/r2<<endl;
    return 0;
}

View Code

实验总结：

1.需要掌握多文件组织结构

2.需要掌握运算符的重载

3.对于类的接口，也最好稍微注意一下

4.我是弟弟，是弟弟，前面都在Ctrl C+V，第三题分数的类，是看了一本书上的代码。

来源：https://www.cnblogs.com/kori/p/10771787.html

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