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

 1 #include<iostream>
 2 using namespace std;
 3 int main()
 4 {
 5     char i;
 6     cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
 7     while(cin>>i)
 8     {
 9         if(i=='A') 
10             cout<<"Data has been added."<<endl;
11         else if(i=='D') 
12             cout<<"Data has been delected."<<endl;
13         else if(i=='S') 
14             cout<<"Data has been sorted."<<endl;
15         else if(i=='Q') exit(0);
16         else 
17             cout<<"Have no choice,please select another one."<<endl;
18         cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
19     }
20        return 0;
21 }

运行结果如下：

（2）用switch语句

 1 #include<iostream>
 2 using namespace std;
 3 int main()
 4 {
 5     char i;
 6     cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
 7     while(cin>>i)
 8     {
 9         switch(i) 
10         {
11             case 'A':cout<<"Data has been added."<<endl;break;
12             case 'D':cout<<"Data has been delected."<<endl;break;
13             case 'S':cout<<"Data has been sorted."<<endl;break;
14             case 'Q':exit(0);
15             default:cout<<"have no choice,please select another one."<<endl;
16         }
17         cout<<"Menu: A(dd) D(elect) S(ort) Q(uit), Select one:";
18     }
19        return 0;
20 }

结果同上。

2、ex 2_29

（1）while循环

 1 #include<iostream>
 2 #include<iomanip>
 3 using namespace std;
 4 int main()
 5 {
 6     int i=2,j,k=0;
 7     while(i<=100)
 8     {
 9         j=2;
10         while(j<=i) 
11         {
12             if(i%j==0) break;
13             j++;
14         }
15         if(i==j) 
16         {
17           cout<<setw(5)<<i;
18           k++;
19         }
20         i++;
21         if(k%5==0) cout<<endl; 
22     }
23        return 0;
24 }

结果如下：

（2）do...while循环

 1 #include<iostream>
 2 #include<iomanip>
 3 using namespace std;
 4 int main()
 5 {
 6     int i=2,j,k=0;
 7     do
 8     {
 9         j=2;
10         do
11         {
12             if(i%j==0) break;
13             j++;
14         }while(j<=i);
15         if(i==j) 
16         {
17           cout<<setw(5)<<i;
18           k++;
19         }
20         i++;
21         if(k%5==0) cout<<endl; 
22     }while(i<=100);
23        return 0;
24 }

（3）for循环

 1 #include<iostream>
 2 #include<iomanip>
 3 using namespace std;
 4 int main()
 5 {
 6     int i,j,k=0;
 7     for(i=2;i<=100;i++)
 8     {
 9         for(j=2;j<=i;j++)  
10             if(i%j==0) break;
11         if(i==j) 
12         {
13           cout<<setw(5)<<i;
14           k++;
15         }
16         if(k%5==0) cout<<endl; 
17     }
18        return 0;
19 }

3、ex 2_32

(1)while循环

 1 #include<iostream>
 2 #include <cstdlib>
 3 #include <ctime>
 4 using namespace std;
 5 int main()
 6 {
 7     srand(time(0));
 8     int m=rand()%100+1,n;
 9     
10     cout<<"Please write down the number you guess:";
11     while(cin>>n)
12     {    
13     if(m<n) 
14         cout<<"What you guess is bigger than the number."<<endl;
15     if(m>n) 
16         cout<<"What you guess is smaller than the number."<<endl;
17     if(m==n)
18         {cout<<"Congratulation!"<<endl;break;}
19     cout<<"Please write down the number you guess:";
20     }
21        return 0;
22 }

（2）do...while循环

 1 #include<iostream>
 2 #include <cstdlib>
 3 #include <ctime>
 4 using namespace std;
 5 int main()
 6 {
 7     srand(time(0));
 8     int m=rand()%100+1,n;
 9     
10     cout<<"Please write down the number you guess:";
11     do
12     {
13        cin>>n;    
14       if(m<n) 
15         cout<<"What you guess is bigger than the number."<<endl;
16       if(m>n) 
17         cout<<"What you guess is smaller than the number."<<endl;
18       if(m==n)
19         {cout<<"Congratulation!"<<endl;break;}
20     cout<<"Please write down the number you guess:";
21     }while(m!=n);
22        return 0;
23 }

效果如下：

4、ex 2_34

 1 #include<iostream>
 2 #include<iomanip>
 3 using namespace std;
 4 enum Balls{red,yellow,blue,white,black}; 
 5 void Print(int a)
 6 {
 7     switch(a)
 8     {
 9         case 0:cout<<setw(10)<<"red";break;
10         case 1:cout<<setw(10)<<"yellow";break;
11         case 2:cout<<setw(10)<<"blue";break;
12         case 3:cout<<setw(10)<<"white";break;
13         case 4:cout<<setw(10)<<"black";break;
14     }
15 }
16 int main()
17 {
18     int n=0,i,j,k; 
19     for(i=red;i<=blue;i++)
20     {
21         for(j=i+1;j<=white;j++)
22         {
23         
24          for(k=j+1;k<=black;k++)
25          { 
26            Print(i);Print(j);Print(k);
27            cout<<endl;
28            n++;
29          }
30        }
31     }
32     cout<<"There are "<<n<<" ways in all."<<endl;
33        return 0;
34 }

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