实验1：c++简单程序设计(1)

//文中有格式错误请无视

//这个编辑器一言难尽

实验目的

---

1. 掌握c++中类c部分的编程知识: 数据类型，常量，变量，运算符，表达式，分支结构，循环结构

2. 掌握C++中数据输入和输出的基本方法

3. 熟练使用c++程序开发环境，掌握c++程序编写、编译、运行、调试的方法

实验准备

---

1. 简单的c++程序结构 学习/复习教材「2.1.3 C++程序实例」

2. c++中数据输入输出的基本方法 学习/复习教材2.3节，学习C++中I/O流、预定义的插入符<<和提取符>>的基本用法。

3. if语句、switch语句、while语句、do…while语句的用法 学习/复习教材2.4节，通过示例理解背后简单算法及c++分支语句、循环语句的用法

4. 自定义数据类型: typedef，枚举类型用法 学习/复习教材2.5节，结合示例理解枚举类型和int型在类型转换时的注意事项

实验内容

---

Part2: 编程练习

教材第2章习题2-28 简单的菜单程序

教材第2章习题2-29 穷举法求质数

教材第2章习题2-32 猜数

教材第2章习题2-34排列组合

实验结论

---

2-28简单的菜单程序（if-else

Code：

 #include<iostream>
 using namespace std;
 int main()
 {
     cout<<"Menu:A(dd) D(elete) S(ort) Q(uit)";
     cout<<"Select one:";
     char k;
     while(cin>>k)
     {
         if(k=='A')
             cout<<"Data has added.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
         else if(k=='D')
             cout<<"Data has deleted.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
         else if(k=='S')
             cout<<"Data has sorted.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
         else if(k=='Q')
             break;
         else
             cout<<"No such choice,please select again.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
     }
     return ;
 }

Screenshot:

(switch

Code:

 #include<iostream>
 using namespace std;
 int main()
 {
     cout<<"Menu:A(dd) D(elete) S(ort) Q(uit)";
     cout<<"Select one:";
     char k;
     while(cin>>k&&k!='Q')
     {
         switch(k)
         {
             case 'A':
                 cout<<"Data has added.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
                 continue;
             case 'D':
                 cout<<"Data has deleted.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
                 continue;
             case 'S':
                 cout<<"Data has sorted.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
                 continue;
             default:cout<<"No such choice,please select again.\n"<<"Menu:A(dd) D(elete) S(ort) Q(uit)"<<"Select one:";
         }
     }
     return ;
 }

Screenshop:

2-29 穷举法求质数（while

Code:

 #include<iostream>
 #include<cmath>
 #include<iomanip>
 using namespace std;
 int main()
 {
     cout<<"1~100间的质数为："<<endl;
     int x=;
     int a,b,c=;
     while(x<=)
     {
         a=sqrt(x);
         if(x!=)
         {
             b=;
             while(x%b!=&&b<=a)
                  b++;
             if(b>a)
             {
                 c++;
                 cout<<setw()<<x;
                 if(c%==)
                     cout<<"\n";
             }
         }
         x++;
     }
     return ;
  } 

Screenshop:

(for

Code:

 #include<iostream>
 #include<cmath>
 #include<iomanip>
 using namespace std;
 int main()
 {
     cout<<"1~100间的质数为："<<endl;
     int x;
     int a,b,c=;
     for(x=;x<=;x++)
     {
         a=sqrt(x);
         if(x==)
             continue;
         else
         {
             for(b=;b<=a;b++)
                 if(x%b==)
                     break;
             if(b>a)
             {
                 c++;
                 cout<<setw()<<x;
                 if(c%==)
                     cout<<"\n";
             }
         }
     }
     return ;
  } 

Screenshop:

(do-while

Code:

 #include<iostream>
 #include<cmath>
 #include<iomanip>
 using namespace std;
 int main()
 {
     cout<<"1~100间的质数为："<<endl;
     int x=;
     int a,b,c=;
     do
     {
         x++;
         a=sqrt(x);
         if(x!=)
         {
             b=;
             do
             {
                 b++;
             }while(x%b!=&&b<=a);
             if(b>a)
             {
                 c++;
                 cout<<setw()<<x;
                 if(c%==)
                     cout<<"\n";
             }
         }
     }while(x<);
     return ;
  } 

 

Screenshop:

2-32 猜数(while

Code:

 #include<iostream>
 #include<ctime>
 #include<cstdlib>
 using namespace std;
 int main()
 {
     int x;
     int a;
     srand(time(NULL));
     x=+rand()%(-+);
     cout<<"Your guess number is(1~100): ";
     cin>>a;
     while(a!=x)
     {
         if(a<x)
         {
             cout<<"Bigger than the number."<<endl;
             cout<<"Your guess number is(1~100): ";
             cin>>a;
         }
         else
         {
             cout<<"Lower than the number. "<<endl;
             cout<<"Your guess number is(1~100): ";
             cin>>a;
         }
     }
     cout<<"Congretulations.You guessed it.~";
     return ;
  }

Screenshop:

(do-while

Code:

 #include<iostream>
 #include<ctime>
 #include<cstdlib>
 using namespace std;
 int main()
 {
     int x;
     int a;
     srand(time(NULL));
     x=+rand()%(-+);
     cout<<"Your guess number is(1~100): ";
     do
     {
         cin>>a;
         if(a<x)
         {
             cout<<"Bigger than the number."<<endl;
             cout<<"Your guess number is(1~100): ";
         }
         else if(a>x)
         {
             cout<<"Lower than the number. "<<endl;
             cout<<"Your guess number is(1~100): ";
         }
     }while(a!=x);
     cout<<"Congretulations.You guessed it.~";
     return ;
  }

Screenshop:

//暴力循环

2-34排列组合(排列

Code:

 #include<iostream>
 #include<iomanip>
 using namespace std;
 int main()
 {
     int x[],k=,i;
     for(x[]=;x[]<=;x[]++)
     {
         for(x[]=;x[]<=;x[]++)
         {
             if(x[]==x[])
                 continue;
             else
             {
                 for(x[]=;x[]<=;x[]++)
                 {
                     if(x[]==x[]||x[]==x[])
                         continue;
                     else
                     {
                         k++;
                         for(i=;i<=;i++)
                         {
                             if(i!=)
                            {
                                 switch(x[i])
                                 {
                                     case :
                                         cout<<"red ";
                                         continue;
                                     case :
                                         cout<<"yellow ";
                                         continue;
                                     case :
                                         cout<<"blue ";
                                         continue;
                                     case :
                                         cout<<"white ";
                                         continue;
                                     case :
                                         cout<<"black ";
                                 }
                             }
                             else
                             {
                                 switch(x[i])
                                 {
                                     case :
                                         cout<<"red\n";
                                         continue;
                                     case :
                                         cout<<"yellow\n";
                                         continue;
                                     case :
                                         cout<<"blue\n";
                                         continue;
                                     case :
                                         cout<<"white\n";
                                         continue;
                                     case :
                                     cout<<"black\n";
                                 }
                             }
                         }
                     }
                 }
             }
         }
     }
     cout<<"Total: "<<k;
     return ;
  }

Screenshop:

（组合

Code:

 #include<iostream>
 #include<iomanip>
 using namespace std;
 int main()
 {
     int x[],k=,i;
     for(x[]=;x[]<=;x[]++)
         for(x[]=x[]+;x[]<=;x[]++)
             for(x[]=x[]+;x[]<=;x[]++)
             {
                 k++;
                 for(i=;i<=;i++)
                 {
                     if(i!=)
                     {
                         switch(x[i])
                         {
                             case :
                                 cout<<"red ";
                                 continue;
                             case :
                                 cout<<"yellow ";
                                 continue;
                             case :
                                 cout<<"blue ";
                                 continue;
                             case :
                                 cout<<"white ";
                                 continue;
                             case :
                                 cout<<"black ";
                         }
                     }
                     else
                     {
                         switch(x[i])
                         {
                             case :
                                 cout<<"red\n";
                                 continue;
                             case :
                                 cout<<"yellow\n";
                                 continue;
                             case :
                                 cout<<"blue\n";
                                 continue;
                             case :
                                 cout<<"white\n";
                                 continue;
                             case :
                             cout<<"black\n";
                         }
                     }
                 }
             }
     cout<<"Total: "<<k;
     return ;
  }

Screenshop:

实验总结

---

这次试验主要是类C的部分，CPP的特性我还没有完全体会到（从I/O流已经可以看出些特点的程度）。

在进行多次判断时还是用switch更方便。

多数时候for循环较为好用。

写程序时尽量避免嵌套过多层循环，严重拖慢编译和运行速度。

srand(time(NULL));

x=1+rand()%(100-1+1);

以此来取一定范围内的随机数。

枚举数据类型不同于整型或字符型。