这是软件工程课写的的第一个代码，主要思路是利用随机数 产生整数 真分数 以及四个代表运算符号的数字，唯一的复杂点事要判断除数是否为零，整数运算使用重新生成随机数的方法，当真分数运算中除数为零时使用分子分母同时加1的方法处理。
本程序主要运用了
rand（）%100产生随机数
srand((int)time(NULL))；做时间种子
课上写思路用时30分钟 实际编写过程中通过网上查资料 问同学 学习以上两个代码 编写时间一个半小时。
#include<iostream>
#include<ctime>
#include<stdlib.h>
using namespace std;
int main()
{
int num1, num2, sym;
srand((int)time(NULL));
for (int i = 1; i < 30; i++)
{
num1 = rand() % 100;
num2 = rand() % 100;
int k = rand() % 2;
sym = rand() % 4;
if (k == 1) //-------------------整数运算
{
if (sym == 0)
{
cout << num1 << "+" << num2 << "=" << endl;
}
if (sym == 1)
{
cout << num1 << "-" << num2 << "=" << endl;
}
if (sym == 2)
{
cout << num1 << "*" << num2 << "=" << endl;
}
if (sym == 3)
{
if (num2 == 0)
{
num2 = rand() % 100 + 1;
cout << num1 << "/" << num2 << "=" << endl;
}
else
cout << num1 << "/" << num2 << "=" << endl;
}
}
if (k == 0) //-------------------真分数运算
{
int a, b, c, d;
a = rand() % 100;
b = rand() % 100;
c = rand() % 100;
d = rand() % 100;
for (;;)
{
if ((a > b&&b !=0)&&(c>d&&d!=0))
{
num1 = b / a;
num2 = d / c;
break;
}
else
a = rand() % 100;
b = rand() % 100;
c = rand() % 100;
d = rand() % 100;
}
if (sym == 0)
{
cout <<b<<"/"<<a<< "+" << d<<"/"<<c << "=" << endl;
}
if (sym == 1)
{
cout << b << "/" << a << "-" << d << "/" << c << "=" << endl;
}
if (sym == 2)
{
cout << b << "/" << a << "*" << d << "/" << c << "=" << endl;
}
if (sym == 3)
{
if (d == 0)
{
num2 = (d+1)/(c+1);
cout << b << "/" << a << " / " << d << "/" << c << "=" << endl;
}
else
cout << b << "/" << a << " / " << d << "/" << c << "=" << endl;
}
}
}
return 0;
}