实验一 c++简单程序设计

一、实验内容

1、ex 2_28

(1) 用if...else判断

 #include<iostream>
 using namespace std;
 int main()
 {
     char i;
     cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
     while(cin>>i)
     {
         if(i=='A')
             cout<<"Data has been added."<<endl;
         else if(i=='D')
             cout<<"Data has been delected."<<endl;
         else if(i=='S')
             cout<<"Data has been sorted."<<endl;
         else if(i=='Q') exit();
         else
             cout<<"Have no choice,please select another one."<<endl;
         cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
     }
        return ;
 }

运行结果如下：

（2）用switch语句

 #include<iostream>
 using namespace std;
 int main()
 {
     char i;
     cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
     while(cin>>i)
     {
         switch(i)
         {
             case 'A':cout<<"Data has been added."<<endl;break;
             case 'D':cout<<"Data has been delected."<<endl;break;
             case 'S':cout<<"Data has been sorted."<<endl;break;
             case 'Q':exit();
             default:cout<<"have no choice,please select another one."<<endl;
         }
         cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
     }
        return ;
 }

结果同上。

2、ex 2_29

（1）while循环

 #include<iostream>
 #include<iomanip>
 using namespace std;
 int main()
 {
     int i=,j,k=;
     while(i<=)
     {
         j=;
         while(j<=i)
         {
             if(i%j==) break;
             j++;
         }
         if(i==j)
         {
           cout<<setw()<<i;
           k++;
         }
         i++;
         if(k%==) cout<<endl;
     }
        return ;
 }

结果如下：

（2）do...while循环

 #include<iostream>
 #include<iomanip>
 using namespace std;
 int main()
 {
     int i=,j,k=;
     do
     {
         j=;
         do
         {
             if(i%j==) break;
             j++;
         }while(j<=i);
         if(i==j)
         {
           cout<<setw()<<i;
           k++;
         }
         i++;
         if(k%==) cout<<endl;
     }while(i<=);
        return ;
 }

（3）for循环

 #include<iostream>
 #include<iomanip>
 using namespace std;
 int main()
 {
     int i,j,k=;
     for(i=;i<=;i++)
     {
         for(j=;j<=i;j++)
             if(i%j==) break;
         if(i==j)
         {
           cout<<setw()<<i;
           k++;
         }
         if(k%==) cout<<endl;
     }
        return ;
 }

3、ex 2_32

(1)while循环

 #include<iostream>
 #include <cstdlib>
 #include <ctime>
 using namespace std;
 int main()
 {
     srand(time());
     int m=rand()%+,n;

     cout<<"Please write down the number you guess:";
     while(cin>>n)
     {
     if(m<n)
         cout<<"What you guess is bigger than the number."<<endl;
     if(m>n)
         cout<<"What you guess is smaller than the number."<<endl;
     if(m==n)
         {cout<<"Congratulation!"<<endl;break;}
     cout<<"Please write down the number you guess:";
     }
        return ;
 }

（2）do...while循环

 #include<iostream>
 #include <cstdlib>
 #include <ctime>
 using namespace std;
 int main()
 {
     srand(time());
     int m=rand()%+,n;

     cout<<"Please write down the number you guess:";
     do
     {
        cin>>n;
       if(m<n)
         cout<<"What you guess is bigger than the number."<<endl;
       if(m>n)
         cout<<"What you guess is smaller than the number."<<endl;
       if(m==n)
         {cout<<"Congratulation!"<<endl;break;}
     cout<<"Please write down the number you guess:";
     }while(m!=n);
        return ;
 }

效果如下：

 4、ex 2_34

 #include<iostream>
 #include<iomanip>
 using namespace std;
 enum Balls{red,yellow,blue,white,black};
 void Print(int a)
 {
     switch(a)
     {
         case :cout<<setw()<<"red";break;
         case :cout<<setw()<<"yellow";break;
         case :cout<<setw()<<"blue";break;
         case :cout<<setw()<<"white";break;
         case :cout<<setw()<<"black";break;
     }
 }
 int main()
 {
     int n=,i,j,k;
     for(i=red;i<=blue;i++)
     {
         for(j=i+;j<=white;j++)
         {

          for(k=j+;k<=black;k++)
          {
            Print(i);Print(j);Print(k);
            cout<<endl;
            n++;
          }
        }
     }
     cout<<"There are "<<n<<" ways in all."<<endl;
        return ;
 } 

效果如下：

二、实验反思

1、注意"A"与'A'的区别，"A"表示字符串，'A'表示字符，比较的是ASCII码。

2、三种循环各具特点，用前应思考其作用，明显看出29题用for循环简洁。

3、生成随机数时，注意头文件cstdlib,ctime;设置域宽时，注意头文件iomanip。

4、使用枚举类型，返回球颜色时，我使用一个了函数将数字与颜色对应。

三、实验小评

https://www.cnblogs.com/fifi1224/p/10555549.html

https://www.cnblogs.com/yinyinzuinihai/p/10556280.html#4213197

https://www.cnblogs.com/sora5934/p/10562100.html