part1：
void Graph::draw() {
int i,a,b,t;
a=size;
b=size;
t=1;
while(a--)
{
for(i=0;i<b-1;i++)
cout<<‘ ‘;
for(i=0;i<t;i++)
cout<<symbol;
for(i=0;i<b-1;i++)
cout<<‘ ‘;
cout<<endl;
b=b-1;
t=t+2;
}
}
part3：
#ifndef FRACTION_H
#define FRACTION_H
#include<iostream>
using namespace std;
class Fraction
{
public:
Fraction (int x = 0, int y = 1);
friend void jia(Fraction a,Fraction b);
friend void jian(Fraction a, Fraction b);
friend void cheng(Fraction a, Fraction b);
friend void chu(Fraction a, Fraction b);
friend void bijiao(Fraction a, Fraction b);
private:
int top;
int bottom;
};
#endif
#include"Fraction.h"
#include<iostream>
Fraction::Fraction(int x, int y) {
top = x;
bottom = y;
}
#include"Fraction.h"
#include<iostream>
using namespace std;
void jia(Fraction a, Fraction b) {
int m, n;
m = a.top*b.bottom + b.top*a.bottom;
n = a.bottom*b.bottom;
cout << m << ‘/‘ << n << endl;
}
void jian(Fraction a, Fraction b) {
int m, n;
m = a.top*b.bottom - b.top*a.bottom;
n = a.bottom*b.bottom;
cout << m << ‘/‘ << n << endl;
}
void cheng(Fraction a, Fraction b){
int m, n;
m = a.top*b.top;
n = a.bottom*b.bottom;
cout << m << ‘/‘ << n << endl;
}
void chu(Fraction a, Fraction b) {
int m, n;
m = a.top*b.bottom;
n = a.bottom*b.top;
cout << m << ‘/‘ << n << endl;
}
void bijiao(Fraction a, Fraction b) {
int m;
m = a.top*b.bottom - b.top*a.bottom;
if (m > 0)
cout << a.top << ‘/‘ << a.bottom;
else
cout << b.top << ‘/‘ << b.bottom;
}
int main() {
Fraction a;
Fraction b(3, 4);
Fraction c(5);
jia(c, b);
jian(c, b);
cheng(c, b);
chu(c, b);
bijiao(c, b);
return 0;
}
实验反思：
1、小球的函数设计十分精妙，要仔细再多看几次。
2、类的定义及实现时要注意各种小细节，这次第三部分就因为一个分号的缺少导致了卡壳，还是掌握的不够熟练。
3、Fraction中要考虑函数的友元用法，刚开始没有想到，怎么也无法实现。就只在fraction.cpp中在类下定义了函数，最后在室友及同学的帮助下想到了友元函数。
原文：https://www.cnblogs.com/yfwg/p/10739568.html