《面向对象程序设计》课程作业（七）

•请将随机生成数字、表达式的部分设计成：一个Random基类，基类中有random()方法。并由该基类派生出RandomNumber类、RandomOperation类，继承并覆盖父类方法。

代码

include

include <stdlib.h>

include<time.h>

using namespace std;

class Random
{
protected:
int digit;
public:
Random(){digit = rand() % 3 + 4;}
~Random(){}
void random();
};

class RandomNumber:public Random
{
protected:
int digit2;
int nums[10];
public:
RandomNumber(){digit2=digit;}
~RandomNumber(){}
void randomN();
};

void RandomNumber::randomN()
{
for (int i = 0; i<digit; i++)
{
nums[i] = rand()%9+1; // 数字
}
}

class RandomOperation:public Random
{
protected:
char signs[10];
public:
RandomOperation(){}
~RandomOperation(){}
void randomO();
};

void RandomOperation::randomO()
{
char c[] = "+-*/";
for (int i = 0; i<digit; i++)
{
signs[i] = c[rand() % 4]; //符号
}
signs[digit] = '=';
}

class Expression:public RandomOperation,public RandomNumber
{
private:
string equ;
stringstream str;
public:
Expression(){}
~Expression(){}
void getExpression();
};

void Expression::getExpression()
{
int braO,braT;
randomN();
randomO();
int bracketNum =rand()%2; //括号个数
if (bracketNum == 1)
{
braO = rand() % (digit2 - 2) + 1;
braT = braO + rand() % (digit2 - braO) + 1;
//braO是第一个括号的位置，braT是第二个括号的位置
}
for (int i = 0; i<digit2; i++)
{
if (bracketNum != 0 && i == braO - 1)
str << "(";
str << nums[i];
if (bracketNum != 0 && i == braT - 1)
str << ")";
if (i != digit2 - 1)
str << signs[i + 1];
}
str <<"=";
str >> equ;
cout<<equ;
}