float transformation(float w)
{float b;b = floor(w * 100 + 0.5) / 100;//用floor函数对运算结果保留小数点后两位 return b;
}

int first_num,second_num,third_num,fourth_num;//用四个整数以分数的形式来构成两个操作数     cout<<"需要列出多少道四则运算?"<<endl;    cin>>n;     cout<<"生成题目数值的范围" <<endl;    cin>>m;     cout<<"————————————————"<<endl;    for(int i=0;i<n;i++)    {        z=rand()%4;        first_num=rand()%m;        second_num=rand()%m;        third_num=rand()%m;        fourth_num=rand()%m;        if (second_num==1)        {            x=(float)first_num;//如果第一个分数的分母为1，则第一个操作数 就等于分子         }        else if(first_num>second_num)//第一个分数为假分数 ，则对调分子与分母，变成真分数             {                t=first_num;                first_num=second_num;               second_num=t;                    }            x=(float)first_num/second_num;        if (fourth_num==1)//如果第二个分数的分母为1，则第二个操作数 就等于分子         {            y=(float)third_num;        }        else if(third_num>fourth_num)//第二个分数为假分数 ，则对调分子与分母，变成真分数             {                t=third_num;                third_num=fourth_num;                fourth_num=t;                            }            y=(float)third_num/fourth_num;

z=rand()%4;switch(z){case 0://运行加法 if(second_num==1 & fourth_num!=1){cout<<i+1<<"、 "<<first_num<<" + "<<third_num<<"/"<<fourth_num<<"="<<"     ";} else if(fourth_num==1 & second_num!=1){cout<<i+1<<"、 "<<first_num<<"/"<<second_num<<" + "<<third_num<<"="<<"     ";}else if(second_num==1 & fourth_num==1){cout<<i+1<<"、 "<<first_num<<" + "<<third_num<<"="<<"     ";}             else{cout<<i+1<<"、 "<<first_num<<"/"<<second_num<<" + "<<third_num<<"/"<<fourth_num<<"="<<"     ";}w=x+y;answer[i+1]=transformation(w);break;case 1:if(second_num==1 & fourth_num!=1){cout<<i+1<<"、 "<<first_num<<" - "<<third_num<<"/"<<fourth_num<<"="<<"     ";} else if(fourth_num==1 & second_num!=1){cout<<i+1<<"、 "<<first_num<<"/"<<second_num<<" - "<<third_num<<"="<<"     ";} else if(second_num==1 & fourth_num==1){cout<<i+1<<"、 "<<first_num<<" - "<<third_num<<"="<<"     ";}             else{cout<<i+1<<"、 "<<first_num<<"/"<<second_num<<" - "<<third_num<<"/"<<fourth_num<<"="<<"     ";}w=x-y;           answer[i+1]=transformation(w);         break;

for(int i=1;i<=n;i++){cout<<"请作答:"<<endl;cout<<i<<"、";cin>>d;if(d==answer[i]){cout<<"恭喜您，回答正确！"<<endl;cout<<endl;right=right+1;}else{cout<<"回答错误，正确答案为："<<setprecision(2)<<answer[i]<<endl;cout<<endl;error=error+1;}}k=(float)right/n;cout<<"回答正确的数量为："<<" "<<right<<"个"<<endl;cout<<"回答错误的数量为："<<" "<<error<<"个"<<endl;cout<<"正确率为："<<" "<<k*100<<"%"<<endl;