#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=0;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=0;;) { int result=( secondnum-thirdnum*fourthnum ) /fifthnum; if( result==0) { 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=0;;) { int result1=(thirdnum*fourthnum ) / fifthnum; if( result1 ==0) //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=0;;) /* 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=0;;) { int flag=firstnum+( secondnum-thirdnum*fourthnum ) /fifthnum ;//有括号的情况下判断是否有余数 if( flag ==0) { 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=0;;) { int flag1= (thirdnum*fourthnum )/fifthnum; if( flag1 ==0) //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）
}
