30道四则运算<2>

#include<iostream>
#include<time.h>
#include<fstream>
#define random() (rand()%100)
using namespace std;

void main()
{
    ofstream outfile;
    outfile.open("a.txt");
    char add='+';
    char sec='-';
    char min='*';
    char div='/';
    int length;
    cout<<"请输入题目数量：";
    cin>>length;

    bool printway;
    cout<<"请选择打印方式  <1>txt文档  <0>屏幕：";
    cin>>printway;

    bool divsion;
    cout<<"请选择是否有除法<1>有除法  <0>无除法：";
    cin>>divsion;

    bool bracket;
    cout<<"请选择是否有括号<1>有括号  <0>无括号：";
    cin>>bracket;

    bool negative;
    cout<<"加减有无负数<1>有负数  <0>无负数：";
    cin>>negative;

    bool remainder;
    cout<<"除法有无余数<1有余数>  <0>无余数：";//先计算结果，再根据条件输出
    cin>>remainder;

    int widestart;
    int wideend;
    cout<<"数值范围(起始---终止)：";
    cin>>widestart;
    cin>>wideend;

    int i;//循环参数
    int j;//循环参数
    int firstnum;
    int secondnum;
    int thirdnum;
    int fourthnum;
    int fifthnum;
     srand((int)time(NULL));

     for( i=;i<length;i++)                       //循环输出length个算式
     {
         firstnum=rand()%wideend+widestart;
        secondnum=rand()%wideend+widestart;
        thirdnum=rand()%wideend+widestart;
        fourthnum=rand()%wideend+widestart;
        fifthnum=rand()%wideend+widestart;

        if(negative)/*if negative =1   当加减存在负数时*/
        {
            if(printway)           //若输出到txt
            {
                outfile<<firstnum;
                outfile<<add;
            }
            else
            {
                cout<<firstnum;
                cout<<add;
            }
            if(bracket)         //若选择有括号输出左括号
            {
                if(printway)
                {
                    outfile<<"(";
                }
                else
                {
                    cout<<"(";
                }
            }                //输出左括号结束
            if(printway)
            {
                outfile<<secondnum;
                outfile<<sec;
                outfile<<thirdnum;
                outfile<<min;
                outfile<<fourthnum;
            }
            else
            {
                cout<<secondnum;
                cout<<sec;
                cout<<thirdnum;
                cout<<min;
                cout<<fourthnum;
            }                              //输出除法之前的数
            if(bracket)
            {
                if(printway)
                {
                    outfile<<")";
                }
                else
                {
                    cout<<")";
                }
            }               //输出右括号

            /*******************************************************************************************有除法有括号没有余数**/
            if(divsion)            //有除法的情况
            {
                    if(bracket)//if have bracket,panduan shifou you yushu
                    {
                        if (!remainder)           //如果没有余数
                        {
                            for(i=;;)
                            {
                                int result=( secondnum-thirdnum*fourthnum )   /fifthnum;
                                if( result==)
                                {
                                    if(printway)
                                    {
                                        outfile<<div<<fifthnum;
                                    }
                                    else
                                    {
                                        cout<<div<<fifthnum;
                                    }
                                    break;
                                }
                                else
                                {
                                    fifthnum=rand()%wideend+widestart;
                                }
                            }
                        }
                    }

                    /**************************************************************************************有除法无括号无余数********/
                    else//meiyou kuohao panduan shifou you yushu
                    {

                        if (!remainder)  //没有余数的情况
                        {

                            for(i=;;)
                            {
                                int result1=(thirdnum*fourthnum  )  /   fifthnum;
                                if(   result1 ==)   //判断是否有余数，若没有，则输出
                                {
                                    if(printway)
                                    {
                                        outfile<<div<<fifthnum<<"="<<endl;
                                    }
                                    else
                                    {
                                        cout<<div<<fifthnum<<"="<<endl;
                                    }
                                    break;
                                }
                                else
                                {
                                    fifthnum=rand()%wideend+widestart;   //若有余数。则重新生成除数
                                }
                            }
                        }

                    }
            }

            if(printway)
            {
                outfile<<"="<<endl;
            }
            else
            {
                cout<<"="<<endl;
            }

        }

        else/* negative=0               没有负数的情况*/
        {
            if(printway)
            {
                outfile<<firstnum;
                outfile<<add;
            }
            else
            {
                cout<<firstnum;
                cout<<add;
            }
            if(bracket)
            {
                if(printway)
                {
                    outfile<<"(";
                }
                else
                {
                    cout<<"(";
                }
            }
            if(printway)
            {
                outfile<<secondnum;
                outfile<<sec;
                outfile<<thirdnum;
                outfile<<min;
                outfile<<fourthnum;
            }
            else
            {
                cout<<secondnum;
                cout<<sec;
                cout<<thirdnum;
                cout<<min;
                cout<<fourthnum;
            }
            for(j=;;)       /*  a+b-c*d/e 则判断b-c*d不能有负数 ，若有负数则循环至 没有*/
            {
                secondnum=rand()%wideend+widestart;
                if(secondnum>(thirdnum*fourthnum))
                {
                    if(printway)
                    {
                        outfile<<firstnum<<add;
                    }
                    else
                    {
                        cout<<firstnum<<add;
                    }
                    if(bracket)
                    {
                        if(printway)
                        {
                            outfile<<"(";
                        }
                        else
                        {
                            cout<<"(";
                        }
                    }
                    if(printway)
                    {
                        outfile<<secondnum<<sec<<thirdnum<<min<<fourthnum;
                    }
                    else
                    {
                        cout<<secondnum<<sec<<thirdnum<<min<<fourthnum;
                    }
                }                    //循环结束

                if(divsion)
                {
                    if(printway)
                    {
                        outfile<<")"<<div;
                    }
                    else
                    {
                        cout<<")"<<div;
                    }
                    if(bracket)//if have bracket,panduan shifou you yushu
                    {
                        if (!remainder)
                        {
                            for(i=;;)
                            {
                                int flag=firstnum+( secondnum-thirdnum*fourthnum ) /fifthnum ;//有括号的情况下判断是否有余数
                                if( flag ==)
                                {
                                    if(printway)
                                    {
                                        outfile<<fifthnum;
                                    }
                                    else
                                    {
                                        cout<<fifthnum;
                                    }
                                    break;
                                }
                                else
                                {
                                    fifthnum=rand()%wideend+widestart;
                                }
                            }
                        }
                        else
                        {
                            if(printway)
                            {
                                outfile<<")";
                                outfile<<div<<fifthnum;
                            }
                            else
                            {
                                cout<<")";
                                cout<<div<<fifthnum;
                            }
                        }
                    }
                    else//meiyou kuohao panduan shifou you yushu
                    {
                        if (!remainder)
                        {
                            for(i=;;)
                            {
                                int flag1= (thirdnum*fourthnum  )/fifthnum;
                                if( flag1 ==)                         //没有括号的情况下判断余数是否为0
                                {
                                    if(printway)
                                    {
                                        outfile<<div<<fifthnum;
                                    }
                                    else
                                    {
                                        cout<<div<<fifthnum;
                                    }
                                    break;
                                }
                                else
                                {
                                    fifthnum=rand()%wideend+widestart;
                                }
                            }
                        }
                        else
                        {
                            if(printway)
                            {
                                outfile<<")";
                                outfile<<div<<fifthnum;
                            }
                            else
                            {
                                cout<<")";
                                cout<<div<<fifthnum;
                            }

                        }
                    }
                    break;
                }        

                if(printway)
                {
                    outfile<<"="<<endl;
                }
                else
                {
                    cout<<"="<<endl;
                }
            }

        }
    }
    outfile.close();
}

我的设计思路是：

先输出一个菜单：多少道题目，输出到屏幕还是文档，是否有除法，是否有括号，是否有负数，是否有余数，以及随机数的范围这几个方面。这几个方面的控制是由bool类型控制的，是为“1”，否为“2”。

我的主函数里面最外层是用一个循环来控制题目的数量。

接下来是一个if。。。else语句，将加减是否有负数进行分类，有负数进入if语句，没有负数进入else语句。

我所设置的括号位置是固定的，都是a+(b-c*d)/e=的样式。有括号的就输出，不选择有括号就输出a+b-c*d/e。

范围带入到rand函数就可以了，输出到屏幕用的是outfile输出，还剩除法和余数两项。

有除法才会有余数，括号又可以影响运算顺序，所以得到嵌套：

if（有负数）

{

if（有除法）

if（有括号）

if（没有余数）

}

else

{

if（有除法）

if（有括号）

if（没有余数）

}