//李俏，2016.3.3
//随机生成四则运算

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
using namespace std;void main()
{int first,second,firstm,secondm;int sign,i,j;srand((int)time(NULL)); //用时间做种子，每次产生随机数都不一样for(i=0;i<30;i++){j=rand()%2;        //选择生成整数运算还是分数运算if(j==0)           //选择整数
        {first=rand()%100;second=rand()%100;sign=rand()%4;switch(sign){case 0:                                   //整数加法cout<<first<<"+"<<second<<"="<<endl;break;case 1:                                    //整数减法if(first>second)cout<<first<<"-"<<second<<"="<<endl;elsecout<<second<<"-"<<first<<"="<<endl;break;case 2:                                     //整数乘法cout<<first<<"*"<<second<<"="<<endl;break; case 3:                                     //整数除法if(second!=0)cout<<first<<"/"<<second<<"="<<endl;elsecout<<second<<"/"<<first<<"="<<endl;break;}}else              //选择分数
        {first=rand()%100;second=rand()%100;//分子firstm=rand()%100;secondm=rand()%100;//分母sign=rand()%4;switch(sign){case 0://分数加法if(firstm!=0&&secondm!=0&&first<firstm&&second<secondm)cout<<first<<"/"<<firstm<<"  +  "<<second<<"/"<<secondm<<"="<<endl;elsei=i-1;break;case 1://分数减法if(firstm!=0&&secondm!=0&&first<firstm&&second<secondm&&(first/firstm)>(second/secondm))cout<<first<<"/"<<firstm<<"  -  "<<second<<"/"<<secondm<<"="<<endl;elsei=i-1;break;case 2://分数乘法if(firstm!=0&&secondm!=0&&first<firstm&&second<secondm)cout<<first<<"/"<<firstm<<"  *  "<<second<<"/"<<secondm<<"="<<endl;elsei=i-1;break;case 3://分数除法if(firstm!=0&&secondm!=0&&first!=0&&second!=0&&first<firstm&&second<secondm)cout<<first<<"/"<<firstm<<"  /  "<<second<<"/"<<secondm<<"="<<endl;elsei=i-1;break;}}}
}